Table of contents

The International Conference on Nanoscience and Technology (ICN&T 2006) was held from 30 July to 4 August 2006 in Basel, Switzerland. At the conference more than 1600 researchers gathered both to mark the anniversaries of STM and AFM and to celebrate the expansion and substantiation of nanoscience in general. The breadth of modern nanoscience and its application was underlined by 40 different topics with more than 500 presentations and 900 posters.

We would like to take this opportunity to thank all authors for their valuable contribution to make these proceedings a comprehensive reflection of the scientific excitement of the ICN&T 2006 conference.

Ernst Meyer, Martin Hegner, Christoph Gerber and Hans-Joachim Güntherodt Editors

The International Conference on Nanoscience and Technology (ICN&T) was held from 30 July to 4 August 2006 in Basel, Switzerland.

The bulk of the papers presented at the conference, after peer review, are published in Journal of Physics: Conference Series.

Invited and plenary papers are published in a special issue of Nanotechnology.

BaTiO₃ nanopowders prepared by using organic acid precursor method were thermally grown onto steel under a vacuum of 10⁻⁵ torr, using an Edwards E-306 coating unit. Reflection measurements of coated steel, in the spectral range 200-1100 nm, were carried out using a double beam spectrophotometer. Characterizations of the deposited layer such as adhesion, hardness, dielectric properties and corrosion resistance have been investigated. Surface morphology of fabricated thin film using scanning electron microscope (SEM) reveal that adhered, dense and void free deposited film enables the coated steel to exhibit high corrosion resistance. The microhardness is improved from 116 HV for uncoated steel to 464 HV for coated ones. Dielectric properties were investigated for coated and pure steel samples. The impedance and phase were found to increase with frequency for the as-deposited samples.

Piezoresistive scanning probe arrays have been developed in view of operation in liquid environments. When the cantilevers are immersed in electrically conductive solutions like for instance physiological buffers, the piezoresistive sensing elements as well as the metal connections have to be passivated. For that purpose, the sensors and the metal wiring were covered with different protective coatings. Long term stability of these passivation layers was demonstrated by imaging in a buffer solution for several hours. Moreover, in view of reducing the damping and thus decreasing the hydrodynamic resistance in liquids, special truss cantilevers have been developed. It was found that this special design conferred no improvement in terms of Q-factor and resonant frequency when operated in water. In order to explain the behaviour of these probes, a theoretical model was established. The model predicted that truss structures could theoretically improve the cantilever performances in liquid, but the probes would need to be operated at high frequency, above 10 MHz.

Pure, Nb-doped and Ag-doped titania nanoparticles were synthesized by sol-gel technique with dopant concentrations ranging from 0.5 to 1.5 atomic percent Nb or Ag. The annealing temperatures ranged from 250 to 900 °C. Changes in phase transformation of the doped samples with reference to pure titania were studied. It was found that Nb doping stablizes the anatase phase while Ag doping accelerates the transformation from anatase to rutile at a concentration higher than 0.5 at. %. The samples were analyzed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Xray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDS).

We have investigated the room temperature growth of C₆₀ overlayers on the strainrelief dislocation network formed by two monolayers of Ag on Pt(111) by means of scanning tunneling microscopy. Extended domains of highly ordered dislocation networks with a typical superlattice parameter of 6.8 nm have been prepared, serving as templates for subsequent C₆₀ depositions. For low C₆₀ coverages, the molecules decorate the step-edges, where also the first islands nucleate. This indicates that at room temperature the C₆₀ molecules are sufficiently mobile to cross the dislocation lines and to diffuse to the step-edges. For C₆₀ coverages of 0.4 monolayer, besides the islands nucleated at the step-edges, C₆₀ islands also grow in the middle of terraces. The C₆₀ islands typically extend over several unit cells of the dislocation network and show an unusual orientation of the hexagonally close-packed C₆₀ lattice as compared to that found on the bare Ag(111) surface. Whereas C₆₀ grows preferentially in a (2 √3 × 2 √3) R30° structure on Ag(111), on the Ag/Pt(111) dislocation network the C₆₀ lattice adopts an orientation rotated by 30°, with the close-packed C₆₀ rows aligned along the dislocations which themselves are aligned along the Ag⟨1-10⟩ directions. For higher coverages in the range of 1-2 monolayers, the growth of C₆₀ continues in a layer-by-layer fashion.

Functional probes such as a metal-tip cantilever and a glass-coated tungsten tip for scanning probe microscopy (SPM) were fabricated utilizing focused ion beam method. Using the functional probes, we obtained results which were hard to reach by usual SPM probes.

The method for calculating the moving, interaction and self organization of nanoparticles is offered. The method is based on the potential built up with the help of the approximation of the numerical calculation results using the method of molecular dynamics of the pair wise static interaction of nanoparticles. With the potential of the pair wise interaction of the nanoparticles, which takes into account forces and moments of forces, the method for calculating the ordering and self-organizing processes, has been developed. The numeric simulation by the methods of molecular mechanics and dynamics were used for investigating the regularities of the amorphous phase formation and the nucleation and spread of the crystalline or hypo crystalline phases over the entire nanoparticle volume depending on the process parameters, nanoparticles sizes and thermodynamic conditions of the ambient.

A complex mathematical model of processes of plant nutrition from a special regulated gas medium containing nanoparticles of basic macro- and microelements is formulated. The variation of the number of nanoparticles and the variation of the total nanoparticle volume with time, which form during the cooling process of the initial gas mixture, were investigated. The calculations of the structures, compositions and shapes of nanoparticles and the movement of nanoparticles were carried out.

Crystalline silver nanowires 60-100 nm in diameter and tens of micrometres in length have been fabricated using a low temperature, solution synthesis technique. We explore the potential of this method to produce functional nanowire structures using two different strategies to attach active molecules to the nanowires: adsorption and displacement. Initially, as-produced silver nanowires capped with a uniaxial-growth-inducing polymer layer were functionalised by solution adsorption of a semiconducting conjugated polymer to generate fluorescent nanowire structures. The influence of nanowire surface chemistry was investigated by displacing the capping polymer with an alkanethiol self-assembled monolayer, followed by solution adsorption functionalisation. The success of molecular attachment was monitored by electron microscopy, absorption and fluorescence spectroscopy and confocal fluorescence microscopy. We examined how the optical properties of such adsorbed molecules are affected by the metallic nanowires, and observed transfer of excitation energy between dye molecules mediated by surface plasmons propagating on the nanowires. Non-contact dynamic force microscopy measurements were used to map the work-function of individual wires, revealing inhomogeneity of the polymer surface coverage.

Ion implantation technique is useful method to dope atoms in a thin layer to make nanoparticles. However, the thermal annealing is required for recovering ion-induced damages and growing NPs. Therefore, the redistribution of implanted atoms in the layer is very important in the formation process of nanoparticles in size and position. We have investigated the redistribution of Ag atoms implanted in a thermally grown 25-nm-thick SiO₂ layer on silicon substrate. Ag negative ions were implanted at 10 keV in the thin oxide layer, where the projected ranges are calculated 12 nm. Samples were annealed at a temperature of 800 degrees or less for 1 h in vacuum with Ar gas flow (50 ml/m). Depth profiles of implanted atoms were investigated by high-resolution Rutherford backscattering spectrometry (HRBS). The formed nanoparticles in the layer were studied by high-resolution cross-sectional transmission electron microscope (XTEM). The samples implanted with Ag negative ions at 10 keV with 5 × 10¹⁵ ions/cm² were measured by HRBS at scattering angle of 80 degree with He ions at 400 keV. Ag atoms distributed at the surface and at a depth corresponded to the calculated profile after annealing at a temperature below 500 °C. It is expected that the surface accumulation of Ag atoms resulted from thermal diffusion of implanted atoms during implantation. At 500 °C, the very small peak in concentration was observed at a depth of 22 nm. This means that a diffusion barrier for Ag atoms exits in this depth. The diffused atoms accumulated at this depth. At 700 °C, the main peak of concentration was appeared at 20 nm in depth, in which FWHM was 7 nm. The XTEM observation showed that the Ag NPs aligned at the same depth of 20 nm along the interface of SiO₂/Si, and that they were nanocrystals (NCs). This mono-layered Ag NCs well corresponded to the HRBS spectra. Thus, we have formed almost mono-layered nanocrystals for Ag implantation in thin silicon dioxide layer.

Single-walled carbon nanotubes (SWNTs) have been synthesized by a laserirradiated chemical vapor deposition (LICVD), where a laser with 514.5 nm was used as a source of heat. The irradiation laser power dependence was investigated for growth of suspended SWNTs. On the basis of the results, the suspended SWNTs were formed between the patterned catalysts at irradiation power of 5 mW by LICVD method. The 514.5-nm Raman scattering spectroscopy measurement revealed that the radial breading mode was clearly observed. As a result of the resonant effect, SWNTs, which are resonant to irradiation laser with 514.5 nm, might be easily bridged between the patterned catalysts.

A new axial method for measuring the friction coefficient with the atomic force microscope is given. This axial method requires no calibration steps and is performed simultaneously with a normal force measurement by measuring the difference between the constant compliance slopes of the extend and retract force curves. The algorithm can be applied retrospectively to extract the friction coefficient from preexisting force measurements. Results are in quantitative agreement with the more established lateral method. The method can be used for both tipped cantilevers and for attached spherical probes.

We present the first findings of the spin transistor effect in the Rashba gate-controlled ring embedded in the p-type self-assembled silicon quantum well that is prepared on the n-type Si (100) surface. The coherence and phase sensitivity of the spin-dependent transport of holes are studied by varying the value of the external magnetic field and the top gate voltage that are applied perpendicularly to the plane of the double-slit ring and revealed by the Aharonov-Bohm (AB) and Aharonov-Casher (AC) conductance oscillations, respectively. Firstly, the amplitude and phase sensitivity of the 0.7.(2e²/h) feature of the hole quantum conductance staircase revealed by the quantum point contact inserted in the one of the arms of the double-slit ring are found to result from the interplay of the spontaneous spin polarization and the Rashba spin-orbit interaction (SOI). Secondly, the values of the AC conductance oscillations caused by the Rashba SOI are found to take the fractional form with both the plateaus and steps as a function of the top gate voltage.

The CV measurements and tunneling spectroscopy are used to study the ballistic transport of the spin-polarized holes by varying the value of the Rashba spin-orbit interaction (SOI) in the p-type quantum well prepared on the surface of the n-CdF₂⟨Y⟩ bulk crystal. The findings of the hole conductance oscillations in the plane of the p-type quantum well that are due to the variations of the Rashba SOI are shown to be evidence of the spin transistor effect, with the amplitude of the oscillations close to e²/h.

Nanostructured diamond doped with sulphur has been prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, carbon disulfide, hydrogen, and argon mixture. The reduction of diamond grains to the nanoscale is relevant to create a network of defective grain boundaries which may be n-type doped to facilitate the transport and injection of electrons to the diamond grains located at the vacuum interface, enhancing the electron field-emission properties of the samples. The downsizing was produced by secondary nucleation and defects induced by sulphur and argon atoms in the chemical vapour deposition surface reactions. Sulphur also acts as an n-type dopant of diamond. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains and the morphology, revealed by field electron scanning microscopy, shows that the grains are in the range of 10 to 30 nm. The lowest threshold achieved for field emission was 13.20 V/μm.

Nanometric sponge-like structures have been prepared from the carburization of polyaniline-(emeradine salt) using a rapid immersion in hot-filament system fed with carbon dioxide, ethyl alcohol and argon. Fiber-like fragments of width in the range of 20 - 40 nm have been observed by field emission scanning electron microscopy (FESEM). Raman measurements suggested that benzenoid rings and amide were present in the carburized samples. Lowest threshold achieved for field emission was 23.5 V/μm.

In this paper the influence of relative humidity on fabrication of nanostructures at GaAs (100) surfaces by local anodic oxidation (LAO) is reported. The attention was paid both to the dimensions of oxide nanolines prepared at different relative humidities for tip-surface voltages of 6 - 9 V and tip speeds of 10 - 200 nm/s, and to the profiles corresponding to line trenches (etched in HCl after the nanoxidation). Contrary to the expectations the height and the half-width of oxide nanolines did not increase with relative humidity in the whole interval from 35% to 90%, but for lower relative humidities (< 50%) the lines were comparable in size to those prepared at 90%. However, this was accompanied with instabilities in the oxidation process resulting most probably from enhanced size variations of the water meniscus between the tip and the surface at these low humidities.

In this paper we study the carrier contribution to elastic constants in quantum confined heavily doped non-linear optical compounds on the basis of a newly formulated electron dispersion law taking into account the anisotropies of the effective electron masses and spin orbit splitting constants together with the proper inclusion of the crystal field splitting in the Hamiltonian within the framework of k.p formalism. All the results of heavily doped three, and two models of Kane for heavily doped III-V materials form special cases of our generalized analysis. It has been found, taking different heavily doped quantum confined materials that, the carrier contribution to the elastic constants increases with increase in electron statistics and decrease in film thickness in ladder like manners for all types of quantum confinements with different numerical values which are totally dependent on the energy band constants. The said contribution is greatest in quantum dots and least in quantum wells together with the fact the heavy doping enhances the said contributions for all types of quantum confined materials. We have suggested an experimental method of determining the carrier contribution to the elastic constants in nanostructured materials having arbitrary band structures.

Esterification of oxidized carbon nanotubes (CNTs) can open a new route for the separation of zigzag and armchair nanotubes. We studied theoretically (by using hybrid DFT within the ONIOM embedding protocol) the reactions of monocarboxy-substituted oxidized tips of zigzag and armchair single-walled CNTs (SWCNTs) with methanol. According to the calculated values of activation energy, Gibbs free-activation barriers, and enthalpies of formation for the SWCNT-(COOH)H5 models, the zigzag nanotube isomer is more reactive as compared to its armchair counterpart. For other models we obtained variable results.

We have used the techniques of atomic force microscopy (AFM) and conductive AFM (C-AFM) to investigate the forward and reverse bias conduction properties of defects in GaN films grown by molecular beam epitaxy (MBE) on metal organic chemical vapor deposition (MOCVD) templates. The surface morphology consists of holes interspersed between undulating spiral ''hillocks'' terminated by pits that have been associated with screw dislocations. For C-AFM measurements, a Pt-coated AFM tip was brought into contact with the GaN surface to form a microscopic Schottky contact. Reverse-bias current leakage is observed for ∼10% of hillocks up to 12 V, and increases to approximately 50% of both hillocks and holes for bias voltages above 25 V. Leakage sites initially occur at ∼10 V and increase substantially in number above ∼15 V.

Carbon nanotubes possess unique chemical, physical, optical, and magnetic properties, which make them suitable for many uses in industrial products and in the field of nanotechnology, including nanomedicine. We describe fluorescent nanocomposites for use in biosensors or nanoelectronics. Then we describe recent results on the issue of cytotoxicity of carbon nanotubes obtained in our labs. Silica nanoparticles have been widely used for biosensing and catalytic applications due to their large surface area-to-volume ratio, straightforward manufacture, and the compatibility of silica chemistry with covalent coupling of biomolecules. Carbon nanotubes-composite materials, such as those based on Carbon nanotubes bound to nanoparticles, are suitable, in order to tailor Carbon nanotubes properties for specific applications. We present a tunable synthesis of Multi Wall Carbon nanotubes-Silica nanoparticles. The control of the nanotube morphology and the bead size, coupled with the versatility of silica chemistry, makes these structures an excellent platform for the development of biosensors (optical, magnetic and catalytic applications). We describe the construction and characterization of supramolecular nanostructures consisting of ruthenium-complex luminophores, directly grafted onto short oxidized single-walled carbon nanotubes or physically entrapped in silica nanobeads, which had been covalently linked to short oxidized single-walled carbon nanotubes or hydrophobically adsorbed onto full-length multi-walled carbon nanotubes. These structures have been evaluated as potential electron-acceptor complexes for use in the fabrication of photovoltaic devices, and for their properties as fluorescent nanocomposites for use in biosensors or nanoelectronics. Finally, we compare the toxicity of pristine and oxidized Multi Walled Carbon nanotubes on human T cells - which would be among the first exposed cell types upon intravenous administration of Carbon nanotubes in therapeutic and diagnostic nanodevices. Our results suggest that carbon nanotubes indeed can be very toxic and induce massive loss of cell viability through programmed cell death at sufficiently high concentrations (>1ng/cell). The cytotoxicity of Carbon nanotubes does depend on many other factors than concentration, including their physical form, diameter, length, and the nature of attached molecules or nanomaterials: carbon black, for instance, is less toxic than pristine CNTs (what shows the relevance of structure and topology); oxidized CNTs are more toxic than pristine CNTs.

Carbon Nanotubes (CN) form a new class of materials that has attracted large interest in the scientific community because of their extraordinary properties (mechanical, electrical, thermal, etc.), as well as owing to the diversity of the proposed technological applications. The characterization of CN is the result of specific sample preparation procedures and requires the use of selected tools (e.g. SEM, HRTEM, EDX, Micro Raman, AFM, STM). We report some studies we carried out based on the CN characterization with the Atomic Force Microscopy (AFM). The general characteristics of the AFM employed and the sample preparation methods are illustrated. The research activities are focused on the development of specific analysis procedures. In fact, the interaction forces between the AFM cantilever tip and the sample, is the main parameter in the acquisition of a 3D topographic AFM micrograph.

A theory is developed for the treatment of magneto transport properties and spin dynamics in magnetic nanowire that contains a domain wall (DW), i.e. a region of non-collinearity. The method is applicable when the wavelength of spin up and down electrons are larger than the DW width in which case the problem is solvable exactly as a spin-resolved scattering from a strongly localized spin-dependent effective potential created by DW. We present calculations for the current-induced spin density, the distribution of the spin currents, and the spin torque acting locally on the magnetic moments within DW. We also discuss an extension based on the weak gradient (adiabatic) perturbation arising after a local transformation to a uniform magnetization.

The preparation of Au/TiO₂(110) planar catalysts and the low temperature (LT) oxidation of CO (in H₂) were investigated by Scanning Tunnelling Microscopy (STM), Auger-electron Spectroscopy (AES) and Thermal Programmed Reaction (TPR). The distribution and the mean size of the Au particles were modified by different pretreatments of the support: (A) Ar⁺ bombardment; deposition to (B) 0.05 ML of K or (C) 0.5 ML of Mo. It was shown that the mean size of the Au particles formed at RT is 3-4 nm on the clean TiO₂(110) surface and this value deacreased to 1.5-2 nm for all pretreated supports. These 2D catalysts were tested in the LT oxidation (PROX) of CO. The same reaction conditions were kept for all experiments: the reaction chamber was filled up to 0.5 hPa O₂, 0.5 hPa CO and 9 hPa H₂ and the temperature of the catalyst was increased from 310 K to 400 K, 450 K or 500K for 60 minutes. The clean, Ar⁺pretreated, K or Mo preexposed oxide surfaces exhibited no activity in the PROX reaction. By the deposition of Au of 1-3 monolayer on to these surfaces, however, an enhancement of CO₂ in the gas phase was clearly detected. The clean TiO₂(110) surface prooved to be the best support for gold, any modification of the support resulted in a loss of the activity. For all cases dependently on the pretreatments, the mean size of the Au particles increased significantly up to 4-8 nm in the PROX at 500 K.

This study examined the effect of process parameters on ferroelectric properties of Pb(Zr, Ti)O₃ (PZT) thin films. Nano-particle PZT ferroelectric thin films were prepared on the Pt/Ti/SiO₂/Si substrates by radio-frequency magnetron sputtering. Experiment parameters including sputtering power, sputtering air pressure, ratio of O₂/Ar, underlay temperature and annealed temperature are analyzed by uniform design. Five levels are set up in suitable and precise range, quadratic regression equations of experiment factors versus experiment responses were set up by step regression. Analysis of variance revealed that developed models were adequate and there is an optimize potential in PZT ferroelectric thin films preparation process by RF-magnetron sputtering.

By using Radio Frequency (RF)magnetron sputtering method, Pb(Zr_0.5Ti_0.5)O₃ (PZT)thin films were deposited on Pt/Ti/SiO₂/Si substrates. Pt/Ti bottom electrode was fabricated on SiO₂/Si substrates by magnetron dual-facing-target sputtering system. Phase and crystalline structure analyses of the PZT films were performed on an X-ray diffraction(XRD), Surface morphology, roughness and particle size of the PZT films were observed with MMAFM/STM+D3100 atomic force microscopy (AFM). Experiment results show that after annealing at 700 °C for 20 min, the thickness of PZT films can get perovskite structure. The surface of PZT thin films was uniform and density. Raw mean, Root Mean Square roughness and Mean roughness of PZT thin films is 34.357nm, 2.479nm and 1.954nm respectively. As test frequency was 1kHz, dielectric constant () of PZT thin films was 327.6, electric hysteresis loop showed that coercive field (Ec), remanent polarization (Pr) and spontaneous polarization(Ps) of PZT thin films were 79.14 kV/cm, 37.78 μC/cm² and 19.10 μC/cm², respectively.

We report on a novel near-field microscope in which ultrashort laser pulses are coupled into hollow-pyramid cantilever probes. The high throughput, absence of polarization pinning and absence of chirping, which are premium features of such probes, enable obtaining sufficient peak power in the near-field to perform nonlinear optical experiments. We show experimental results on second-harmonic generation from metal nanostructures and two-photon excitation of fluorescent conjugated polymers on the subwavelength scale.

The purpose of this study is to analyse the influence of the chemical contribution on the nano-friction of polystyrene. The role of interfacial interactions is analysed by comparing friction between the polymer and hydrophobic AFM tip (methyl-terminated grafted layer) and hydrophilic tip (hydroxyl-terminated tip) as a function of sliding velocity and normal force. Nano-friction experiments are achieved by using atomic force microscopy (AFM) in torsion mode. Amorphous atactic polystyrene films are prepared by spin coating a solution onto a smooth and rigid substrate (silicon wafer). Two amorphous atactic polystyrene, varying by their different molecular weights are used. Experimental results show that the friction coefficients measured with hydroxylated tip are always larger than those obtained with non-treated tip (intermediate value) and hydrophobic tip (lower friction), indicating a relationship between nano-friction and interfacial interactions. The dependence of frictional force on velocity is consequent, with a great increase of friction with speed in the case of the hydroxylated tip. A higher friction is obtained for the higher molecular weight polystyrene in contact with hydroxylated tips. However, differences between both polymers become negligible in the case of non-treated and hydrophobic tips.

Adhesive properties of a polymer surface results from the complex contribution of surface chemistry and activation of sliding and dissipating mechanisms within the polymer surface layer. The purpose of this study is to dissociate the different contributions (chemical and mechanical) included in an AFM force-distance curve in order to establish relationships between the surface viscoelastic properties of the polymer, the surface chemistry of functionalized polymer surfaces and the adhesive forces, as determined by C-AFM experiments. Indeed we are interested in the measurements of local attractive or adhesive forces in AFM contact mode, of controlled chemical and mechanical model substrates. In order to investigate the interplay between mechanical or viscoelastic mechanisms and surface chemistry during the tip - polymer contact, we achieved force measurements on model PDMS polymer networks, whose surfaces are chemically controlled with the same functional groups as before (silicon substrates). On the basis of AFM nano-indentation experiments, surface Young moduli have been determined. The results show that the viscoelastic contribution is dominating in the adhesion force measurement. We propose an original model, which express the local adhesion force to the energy dissipated within the contact and the surface properties of the material (thermodynamic work of adhesion). Moreover we show that the dissipation function is related to Mc, the mass between crosslinks of the network.

Inhomogenities of the b* surface component of the CDW wave vector, probed by LT-UHV-STM, were observed at the (-201) surface of quasi-1D blue bronze Rb_0.3MoO₃cleaved in-situ. Whereas on the scale of tens of nanometers, the CDW wave vector might be constant, significant changes were observed on the scale of microns in STM measurement. On the basis of first-principles DFT calculations, it is found that these inhomogenities could be due to a change in the stoichiometry of surface alkali atoms taking place after the cleavage process. It is shown that differences in the stoichiometry of surface alkali atoms change the filling of the partially filled bands of the top most layer. Consequently, in equilibrium with the bulk layers, this results in a local surface potential that changes the surface nesting vector and hence the periodicity of the CDW modulation. The DFT predictions for the changes in surface nesting vector are consistent with the observed experimental inhomogenities probed by STM.

We have investigated both q₁ and q₂ charge-density wave transitions occuring in NbSe₃ by means of low temperature scanning tunneling microscopy under ultra-high vacuum on in-situ cleaved (100) surface. High-resolution topographical images with molecular resolution were obtained in the temperature range between 5K and 140K. We studied the temperature dependency of the order parameters of both transitions using Fourier transform of the STM images. Our results show that at the free (100) NbSe₃ surface, the low temperature q₂ CDW transition occurs above 70K, i.e. more than 10K above the bulk transition temperature reported by x-ray diffraction experiment or by tunneling junction measurements involving an unfree NbSe₃ surface. We propose that as q₂ phonon modes in NbSe₃possess a component transverse to the surface, they might be softer in the top layer than in the bulk, leading to an extraordinary phase transition for the q₂ CDW at surface. Additionnally, at variance with previously reported STM measurements, our images show a bias voltage polarity dependency that could be interpreted in a lower density of states on Se atoms of chain II for the occupied states than for the empty states.

We study hole spin transport in semiconductor systems with total angular momentum J = 3/2. By deriving an expression for the polarisation vector we show that the in-plane polarisation vanishes whenever only heavy hole channels are open in the leads. We further derive a set of constraints on the spin transport through a symmetry analysis and study the hole spin Hall effect in the presence of randomly distributed scatterers.

We report on a technique able to create low-energy hydrogen ions induced defects on single walled carbon nanotubes (SWCNT) using a hydrogen electron cyclotron resonance (ECR) plasma source. Low temperature scanning tunneling microscopy (LT-STM) investigations revealed defect sites with hillocks-like features between 1 Å and 3 Å in height and lateral spreading between 0.5 nm and 2 nm. Scanning tunneling spectroscopy (STS) measurements on a metallic SWCNT revealed a strong modification of the electronic structure on a specific defect zone characterized by a pronounced peak in the local density of states (LDOS) close to the Fermi energy.

Sublimation of SiO is used to protect PVD aluminium flakes from water corrosion and to generate highly porous SiO₂ flakes with holes in the nanometer range. SiOx/Al/SiOx sandwiches were made as well as Ag loaded porous SiO₂ as antimicrobial filler.

Nano-mechanical properties of single biomolecules and polymers as well as interaction forces between specific molecular pairs have been intensively studied during the last two decades by using atomic force microscopy with force measurement technique. In these experiments, molecules were pulled up from the substrate in vertical direction. However, it is also interesting to develop a similar lateral force-distance technique in which sample molecules stay lain on the solid surfaces during mechanical stretching. Thus, wider possibilities can be opened up to study the stretched macromolecules by other microscopy/spectroscopy methods. Since typical atomic force microscopes have the lateral scanner ranges up to ∼100 μm, very long macromolecules can be studied and manipulated in this way. As an example, up to 8 μm stretching of self-polymerized poly(ethylene glycol)-bis-thiol on gold surface was observed. It was also confirmed that even in the lateral force-distance curves (50-300 nm above surface), the vertical cantilever bending, not torsion, was mainly responsible for the observed deflection signal. This made lateral force data analysis simpler since the normal force constants are easier to estimate than torsion ones. The force curves in our method were also free of any interference fringes. They had horizontal and easy identifiable baselines.

Hyperfine interaction of electron spins with nuclear spins, in coupled double quantum dots is studied. Results of successive electron spin measurements exhibit bunching due to correlations induced via the nuclear spins. Further nuclear spins can be purified via conditional electron spin measurements which lead to electron spin revivals in the conditional probabilities. The electron spin coherence time can be extended via conditional measurements. The results are extended to a single electron on a single QD.

Ground and multi excited state photoluminescence, as well as its temperature dependence, in InAs quantum dots embedded in symmetric In_xGa_1-xAs/GaAs (x = 0.15) quantum wells (DWELL) have been investigated. The solution of the set of rate equations for exciton dynamics (relaxation into QWs or QDs and thermal escape) solved by us earlier is used for analysis the variety of thermal activation energies of photoluminescence thermal quenching for ground and multi excited states of InAs QDs. The obtained solutions were used at the discussion of the variety of activation energies of PL thermal quenching in InAs QDs. It is revealed three different regimes of thermally activated quenching of the QD PL intensity. These three regimes were attributed to thermal escape of excitons: i) from the high energy excited states of InAs QDs into the WL with follows exciton re-localization; ii) from the In_xGa_1-xAs QWs into the GaAs barrier and iii) from the WL into the GaAs barrier with their subsequent nonradiative recombination in GaAs barrier.

We present a new tool and measurement protocol based on Atomic Force Microscopy for the AC and DC electrical characterization of biological samples at the nanoscale. The new developments allow performing a variety of electrical measurements (DC conductivity, A C small signal impedance) both in spectroscopic mode (i.e. in a single point) as well as in imaging mode (i.e. by providing a map of the electrical properties with nanometric spatial resolution) with minimum sample damage. Successful test measurements have been carried out on Purple Membrane.

We have observed one-dimensional (1D) superlattices at the grain boundary of highly ordered pyrolytic graphite (HOPG) with a scanning tunneling microscopy (STM). Observed 1D superlattices extend over micrometer length and have periodicities from 0.5 nm to 10 nm with a height corrugation up to 1.5 nm, due to electron density effects, which is 15 times larger than the graphite lattice corrugation observed with STM. Experimental observations are well explained by a simple model based on the complex electron interference at the grain boundary between two misoriented graphite layers.

We report the results of first-principles theoretical calculations for the electronic structure of aluminate nanotubes. A tubular structure in the form of AlO₂ is energetically stable and exhibits metallic conduction. Due to weak interactions between Li atoms and nanotubes, Li doping does not alter the stability of AlO₂ nanotubes and only increases the Fermi level. On the other hand, stable AlO nanotubes can be obtained by hole doping with Be and Mg impurities.

Individual carbon nanorod was fabricated on a tungsten needle tip by electron beam induced deposition. Precursor was phenanthrene (C₄H₁₀) and deposition experiment was done using a scanning electron microscope at room temperature. Tungsten needle tip together with the as-deposited nanorod was mounted inside a specially designed transmission electron microscope (TEM) specimen holder and its field electron emission properties were investigated in situ. Relationship between micro-structure and emission property of the nanorod was established. It was found that the surface structure at the top of nanorod, such as a small protrusion within only several nanometers scale, has significant influence on the field emission property. An emission current of several tens of nano-ampere flowing through this nanorod could induce resistance heating. In several minutes, this thermal energy could transform the original amorphous carbon into a graphite-like structure embedded with fullerenes. The turn-on voltage of the graphite-like nanorod was about 11 V less than that of the original amorphous case.

X-ray spectra from the surface of insulating samples were measured using a 30 kV Ga⁺ focused ion beam instrument equipped with an energy dispersive X-ray spectrometer, showing an intense emission of low energy X-rays from insulating materials such as Al-K and O-K of Al₂O₃. This low energy ion induced X-ray emissions (LIIXE) from insulating materials is expected as a new analytical technique for light elements in insulating samples. It was found that X-ray yield induced by Ga⁺ ion beam irradiation depends on the incident beam energy. It was also found that high voltage of a secondary electron detector located near the sample strongly influences the intensity of X-ray emission, implying that bombardment of electrons, which may come from the chamber wall, onside the sample surface is a key phenomenon for the X-ray emissions.

Scanning Microdeformation Microscopy (SMM) is a dynamic force microscopy technique, which uses a microcantilever vibrating at its resonance frequency (range of some kHz up to several 10 kHz) while scanning a sample surface. It uses a microcantilever associated with a tip of radius in the 1-20 microns range (contact radius is typically about 1 μm). The absolute amplitude and phase of the cantilever vibration as well as the frequency shifts of the cantilever resonance frequencies are measured. Due to the size of the tip, the SMM works on mesoscopic scale, allowing to investigate a large subsurface volume (typically about 10 times the contact radius between the tip and the sample). This paper is devoted to the contrast analysis in the SMM for the investigation of subsurface defects. More precisely we analyse different mechanical approaches to explain the contrast induced by the defects in the subsurface volume. The approach used for each case depends on the materials and geometry (size, depth, elastic properties). Experimental results performed on calibrated samples are presented, allowing us to give a clear analysis of the contrast sources.

We study the behavior of hydrogen molecules between atomic-sized metallic electrodes using the mechanically controllable break junction technique. We focus on the interaction H₂ with monoatomic gold chains demonstrating the possibility of a hydrogen molecule being incorporated in the chain. We also show that niobium is strongly reactive with hydrogen, which enables molecular transport studies between superconducting electrodes. This opens the possibility for a full characterization of the transmission properties of molecular junctions with superconducting subgap structure measurements.

Experiments on Highly Oriented Pyrolytic Graphite (HOPG) demonstrate that ultrasonic-assisted actuation with the tip of an Atomic Force Microscope (AFM) cantilever can induce stacking modifications and folding of triangular-shaped HOPG surface flakes. We have generated permanent displacements of buried dislocations that require stacking changes of extended graphene layers by repeatedly scanning over a same surface region. In this contribution, I discuss the opportunities of ultrasonic AFM to improve fabrication technologies on the nanometer scale and realize subsurface modification via near-field actuation.

We report on a novel technique, Mechanical-Diode Mode Ultrasonic Friction Force Microscopy, based on the study of the additional ultrasound-induced torsion of a cantilever when the cantilever tip scans in contact with a sample surface at low frequency in the presence of shear surface ultrasonic vibration of sufficiently high amplitude (lateral mechanical-diode effect). Data recorded on Si(111) are discussed. The results can be understood by considering the interaction of the tip with the lateral surface sample potential, and the presence of an ultrathin viscous liquid layer at the tip-sample contact which develops hydrodynamic pressure when sheared at ultrasonic velocities.

Lu₂O₃ thin film has been deposited on n-type (100) Si substrates using pulsed laser deposition (PLD). Atomic Force Microscopy (AFM) revealed a relatively smooth film surface after high temperature annealing at 900 °C with roughness root mean square (rms) value of 0.237 nm. A equivalent oxide thickness (EOT) of 1.68 nm with a leakage current density of 1 × 10⁻⁴ A/cm² at 1 V accumulation bias and a k value of 11.6 was obtained for 4.5 nm thick Lu₂O₃ thin film deposited at room temperature followed by post-deposition anneal (PDA) at 900 °C in oxygen ambient. High resolution transmission electron microscopy (HRTEM) analysis has shown that Lu₂O₃ film remains amorphous at high temperature annealing at 900 °C with little or no observable interfacial layer. The results showed that Lu₂O₃ possesses good properties and has strong potential as an alternative high-k gate dielectric.

We report the results of inelastic electron tunneling spectroscopy (IETS) on the ab plane (c-axis tunneling) of a slightly underdoped twinned NdBa₂Cu₃O_x single crystal (T_c = 93.5 K) performed with a scanning tunneling microscope at T = 4.2 K. In the energy derivative (d²I/dV²) of the differential conductivity curves having coherence peak, dip and hump structures, we observe a resonance peak at 24±2 meV. Here we discuss the possible origin of this inelastic scattering peak.

Mechanically Controllable Break-Junctions were used to study the physical adsorption of hydrogen molecules on the surfaces of W, Mo and Ta as well as their subsequent chemisorption and dissociation and diffusion of protons into the bulk of the material. Dissolving of hydrogen into Ta is accompanied by 1/f^αresistance noise with 1.2 < α < 1.7 depending on the contact diameter.

This paper presents results of the non-contact and non-destructive characterization of porous SiC layers using Raman scattering spectroscopy, scanning electron microscopy as well as atomic force microscopy methods. The comparative study of the Raman spectroscopy on the bulk SiC and porous SiC layers has shown a number of new features specific for nanocrystallite materials, which have been analyzed and discussed.

Carbon nanotube networks were assembled by dielectrophoresis on microelectrodes and their response to temperature was monitored. The stability of the networks was investigated in order to determine their suitability for use as electrical components or sensors. Our results suggest that the networks cannot readily be used for these applications since their behaviour depends greatly on the amount of oxygen adsorbed on their surfaces.

The electronic structures of one-dimension carbon nano wires, nano rings of C₁₀ to C₂₂ and hydrogen end-capped carbon nano wires of HC_2nH (n = 8-13) have been investigated based on time-of-flight (TOF) mass spectroscopy, laser spectroscopy and first principle ab initio calculations. The size-selected carbon nano molecular wires and rings were investigated on-line using a two-color laser spectroscopic method. The ab initio predicts that the linear structures of the pure carbon nano molecular wires are about 3 eV higher in energy compared to those of the ring structures with similar size. The ring structure with bond length alternation (Peierls'dimerization) is unstable at size up to C₂₂ ring. The optical transition energies were calculated using the timedependent density functional theory (TD-DFT) and the CASSCF approach. For longer wires, it seems that the C_4n+2wires are metallic and the hydrogen end-capped carbon wires could be semiconductors.

Robotic manipulation at the nanometer scale is a promising technology for structuring, characterizing and assembling nano building blocks into nanoelectromechanical systems (NEMS). Combined with recently developed nanofabrication processes, a hybrid approach to building NEMS from 3D SiGe/Si/Cr and Si/Cr nanostructures is presented. Nanosensors and nanoactuators are investigated from experimental, theoretical, and design perspectives.

The transfer of a CO molecule from the Cu(111) surface towards the STM tip, induced by the tunnelling current, occurs only if a threshold voltage of 2.4 eV is exceeded (Bartels L, Meyer G, Rieder K-H, Velic D, Knoesel E, Hotzel A, Wolf M and Ertl G 1998 Phys. Rev. Lett.80 2004). We present a theory based on the Quantum Nano Dynamics (QND) approach, treating the competition between a coherent and a decoherent mechanism of current induced CO desorption via inelastic tunnelling and vibrational excitation. The keypoint of the theory is to regard the tunnelling process as driving the system in a transient excited state and to include explicitely many-particle relaxation effects in the excited state. Only a decoherent desorption mechanism via a transient negative ion resonance of the sample surface, which is created through electron injection and interacts with the CO molecule, provides an explanation for the existance of the voltage threshold for CO desorption and reproduces the quantum yield and the isotope effect as observed in the STM experiment.

The manufacture of nanowires and the exploitation of their specific properties are the great fields of fundamental and industrial research. Some nanostructuration can be obtained with the help of conventional lithography technics; nevertheless these technics are limited by the optical resolution, the introduction of many defects and the residual damage related to engraving. A new approach, which consists to create nanowires in-situ on pre structured SmSi(111) interface has been investigated by scanning tunneling microscopy (STM). This interface is known to permit the creation of many different 1D templates in the submonolayer range. We show in this study, the possibility to create Fe nano-objects of well-defined size distributed in an ordered array.

An important mechanism in spintronics is spin-splitting induced by structure and/or bulk inversion asymmetry. These effects are frequently assumed to depend on two parameters usually denoted by α and β respectively, and α is assumed to be proportional to some average electric field. We here demonstrate that the spatial dependence of the electric field gives very important effects absent in simpler models. These effects are particularly clear in wide modulation-doped quantum wells where there are two weakly interacting electron gases in the interface regions. Using an 8 × 8 k . p matrix approach we obtain anticrossings between interacting subbands at which the spin direction and/or wave function localization are found to be strong functions of the in-plane wave vector.

Experiments of the scanning tunnelling microscopy and spectroscopy (STM/STS) have been carried out on the layered superconductor MgB₂ with T_c = 39 K. The measurements were done at 5 K using a Pt-Ir tip and the single-crystal grain. The STM images show characteristic hexagonal patterns with the distances of nearest neighbour atoms to be 0.3 - 0.35 nm and 0.15 - 0.2 nm, respectively, which are consistent with the Mg and B lattice sizes. The STS measurements clarify the superconducting gap 2Δ = 20 - 24 meV, which leads to the strong-coupling ratio 2Δ/k_BT_c = 5 - 6. The tunnelling spectra can be described by the correlated 2-gap model. These features are consistent with our previous break-junction measurements. The gap structure is homogeneous at least within the range of 200 nm × 200 nm.

Photoconductivity of germanium nanowire arrays of 50 and 100 nm diameter incorporated into Anodic Aluminum Oxide (AAO) membranes illuminated with visible light is investigated. Photocurrent response to excitation radiation with time constants faster than 10⁻⁴ s were governed by absorption of incident light by nanowires, while photokinetics with time constants of the order of 10⁻³ s originates from the photoluminescence of the AAO matrix. Possible applications of nanowire arrays inside AAO as photoresistors are discussed.

In this paper, we propose using a nanoscale spin-wave-based architecture for implementing neural networks. We show that this architecture can efficiently realize highly interconnected neural network models such as the Hopfield model. In our proposed architecture, no point-to-point interconnection is required, so unlike standard VLSI design, no fan-in/fan-out constraint limits the interconnectivity. Using spin-waves, each neuron could broadcast to all other neurons simultaneously and similarly a neuron could concurrently receive and process multiple data. Therefore in this architecture, the total weighted sum to each neuron can be computed by the sum of the values from all the incoming waves to that neuron. In addition, using the superposition property of waves, this computation can be done in O(1) time, and neurons can update their states quite rapidly.

Atomic Force Acoustic Microscopy has been proven to be a powerful technique for materials characterization with nanoscale lateral resolution. This technique allows one to obtain images of elastic properties of materials. By means of spectroscopic measurements of the tip-sample contact-resonance frequencies, it is possible to obtain quantitative values of the mechanical stiffness of the sample surface. For quantitative analysis a reliable relation between the spectroscopic data and the contact stiffness is required based on a correct geometrical model of the cantilever vibrations. This model must be precise enough for predicting the resonance frequencies of the tip-sample interaction when excited over a wide range of frequencies. Analytical models have served as a good reference for understanding the vibrational behavior of the AFM cantilever. They have certain limits, however, for reproducing the tip-sample contact-resonances due to the cantilever geometries used. For obtaining the local elastic modulus of samples, it is necessary to know the tip-sample contact area which is usually obtained by a calibration procedure with a reference sample. In this work we show that finiteelement modeling may be used to replace the analytical inversion procedure for AFAM data. First, the three first bending modes of cantilever resonances were used for finding the geometrical dimension of the cantilever employed. Then the normal and in-plane stiffness of the sample were obtained for each measurement on the surface to be measured. A calibration was needed to obtain the tip position of the cantilever by making measurements on a sample with known surface elasticity, here crystalline silicon. The method developed in this work was applied to AFAM measurements on silicon, zerodur, and strontium titanate.

Nanoscale dispensing (NADIS) has been recently developed for liquid deposition and manipulation. In NADIS, atomic force microscope probe milled by a focused ion beam was used for nanoscale dispensing of liquid. We present an approach to control the size of dispensed droplets by several parameters such as the aperture size on the probe, the surface energy of both tip outer wall and sample surface. A fine control of the droplet size down to the nanometric scale may provide potentials for surface nanopatterning of molecule deposition.

We elaborate on a number of issues concerning our recent proposal for spin-qubit manipulation in nanowires using the spin-orbit coupling. We discuss the experimental status and describe in further detail the scheme for single-qubit rotations. We present a derivation of the effective two-qubit coupling which can be extended to higher orders in the Coulomb interaction. The analytic expression for the coupling strength is shown to agree with numerics.

We have made a Dynamic Nanoindentation Microscope (DNM) setup based on sample modulation, in order to allow a direct comparison between various dynamical mechanical measurement techniques such as Force Modulation Microscopy (FMM) and Dynamic Mechanical Analysis (DMA). The microscope is integrated to a standard Atomic Force Microscope (AFM) and uses a commercial nanoindentation system. Instead of the standard bimorph and force modulation configuration, we used a stacked ceramic sample actuator in displacement modulation. Both DMA measurements and DNM imaging were performed on each sample for the determination of the reduced, storage and loss modules, and a good agreement between the techniques have been found. Compared to FMM, we show that DNM has the advantage of always keeping the same contrast in the viscoelastic images as a function of the frequency.

We present series of first-principles calculations for both pure and hydrogen contaminated gold wire systems in order to investigate how such impurities can be detected. We show how a single H atom or a single H₂ molecule in an atomic gold wire will affect forces and Au-Au atom distances under elongation. We further determine the corresponding evolution of the low-bias conductance as well as the inelastic contributions from vibrations. Our results indicate that the conductance of gold wires is only slightly reduced from the conductance quantum G₀ = 2e²/h by the presence of a single hydrogen impurity, hence making it difficult to use the conductance itself to distinguish between various configurations. On the other hand, our calculations of the inelastic signals predict significant differences between pure and hydrogen contaminated wires, and, importantly, between atomic and molecular forms of the impurity. A detailed characterization of gold wires with a hydrogen impurity should therefore be possible from the strain dependence of the inelastic signals in the conductance.

We studied initial atomic hydrogen adsorption onto Si(111) 7 × 7 adatoms by scanning tunnelling microscopy in an ultrahigh vacuum. Adatom reaction probabilities were measured as a function of atomic hydrogen exposure time for room-temperature and hightemperature surfaces. Hydrogen uptake was well represented by Langmuir adsorption at 361 and 414 K, while depression of uptake was seen at 481 K after one of six adatoms was terminated by hydrogen. Hydrogen adsorption had positive adsorption correlations between adjacent centre adatoms and corner adatoms across the 7 × 7 half unit. These correlations were enhanced at 481 K. In accordance with the positive reaction correlation between these adjacent adatoms, the average number of reacted adatoms in adjacent 7 × 7 half units was also enhanced as the number of reacted adatoms increased in the half unit.

We have investigated the Au-induced nanofaceting of vicinal silicon surfaces tilted from [111] towards [11]. Using samples miscut 3.8°, and 8°, from [111] respectively we have used scanning tunnelling microscopy (STM) to measure the surface morphology as a function of Au coverage (0.04 to 0.44 ML). As expected, Au adsorption produces dramatic changes in surface morphology on both samples. On the 3.8° sample we find that as little as 0.04 ML of Au is sufficient to remove the faceting present on the clean surface. As more Au is deposited 1-dimensional chain structures nucleate at step edges. These chain structures eventually grow to form (775)-Au facets. At 0.17 ML we observe a surface with Si(111)7 × 7 terraces and (775)-Au nanofacets. With more Au, the (111) terraces transform from a 7 × 7 to a 5 × 2 reconstruction and at 0.4 ML the sample consists of Si(111)5 × 2-Au terraces separated by (775)-Au facets. The morphology of the 8° sample also depends critically on Au coverage. Below 0.32 ML all 8° surfaces include (775)-Au nanofacets. Above 0.32 ML, the (775)-Au facet is no longer stable and Au is accommodated on the surface via the formation of higher angle facets with smaller chain spacing. In both samples, the persistence of the (775)-Au facet reinforces the idea that it represents a low energy facet on these Au modified vicinal surfaces.

We have investigated the surface potential change accompanying the variation in diamond surface chemisorbed structures using scanning Maxwell-stress microscopy. The hydrogen chemisorbed diamond surface was prepared by a hydrogen plasma treatment following the homoepitaxial (001) diamond growth by the microwave plasma-assisted chemical vapor deposition (MPCVD). The surface chemisorbed structure was controlled by increasing the oxidized temperature in the range from 100 °C to 500 °C. The hydrogen chemisorbed diamond surface showed a minimum work function value of 4.8 eV. A thermal oxidation of the hydrogen chemisorbed diamond surface at 500 °C yielded the oxygen chemisorbed diamond surface, which showed a maximum work function value of 5.8 eV. The surface potential value, which corresponds to the surface work function value, was strongly influenced by the species of the chemisorption on the diamond surface.

We have investigated the electrical conductivity change that occurs by oxidation of a homoepitaxially grown diamond (100) surface. For this purpose, atomically flat diamond (100) surfaces homoepitaxially grown by a microwave plasma-assisted chemical vapor deposition (MPCVD) were prepared. It is well-known that a CVD-grown diamond surface is a hydrogen-chemisorbed structure. Surface chemisorbed structures of diamond can be controlled by oxidation in air at temperatures from 25 °C up to 350 °C. The degree of oxygen-chemisorption on the diamond surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The electrical resistivity (or conductivity) of the diamond surfaces was measured at room temperature under nitrogen flow by using the van der Pauw four-probe system. The surface resistivity of diamond was drastically increased at 300-350 °C, a temperature range corresponding to the beginning point of surface oxidation of a diamond analyzed by the XPS.

This paper reports on the investigation of dynamic magnetization reversal process in electrodeposited nanocrystalline Ni and Ni₈₀Fe₂₀ films by employing nanosecond magnetic pulse technique. The surface morphology has been investigated using SEM, EDAX, XRD and AFM analyses and static magnetic properties of the films are characterized by vibrating sample magnetometer (VSM). Two different techniques are designed and employed to study the nanosecond magnetization reversal process in nanocrystalline thin films: Magneto-Optical Kerr Effect (MOKE) and nanosecond pulsed field magnetometer. Results of dynamical behavior as a function of several variables such as magnitude of applied bias magnetic field, amplitude and width of the pulsed magnetic field are analyzed in detail using both techniques. A computer simulation package called Object Oriented Micro-Magnetic Framework (OOMMF) has been used to simulate the magnetic domain patterns of the samples.

Nanomechanical sensors based on cantilever technology allow the measurement of various physical properties. Here we present a software for the comprehensive analysis of such data. An example for the combined measurement of mass and surface stress is presented.

The determination of the mechanical properties of polymer-surfaces is a widespread task in the AFM community. The most important step in measuring is the thorough calibration of the measurement setup. Here, we address that problem for the case of Digital Pulsed Force Mode measurements. We show that following our suggestions, one can get reliable and consistent quantitative data on the mechanical properties of polymers such as PMMA or SBR rubber. The influence of the individual cantilevers and their properties, as well as the variations due to the settings of the AFM are widely eliminated.

Regularities of nanowire formation by thinning silicon whiskers at high-temperature oxidation in the range 900-1050 °C were studied. The oxidation was performed in a flow of dry or wet oxygen. It is shown that a stopping of the oxidation process occurs at oxidation temperature below ~960 °C. For example, at 930 °C the oxidation process is stopped in 6 hours. It is shown that at temperature above 960 °C such a stopping mechanism does not act and a through oxidation of the whisker is possible. In the wet oxygen, similar through oxidation takes place even at 930 °C. On the other hand, during oxidation above 960 °C it is possible to prepare nanowires with diameter lower than 5 nm in relatively thick whiskers; this is convenient for further manipulation with such objects. For example, during oxidation at 1000 °C nanowires with diameter ≤5 nm in an oxide shell up to 200 nm were prepared. Also, it has been shown that gold as a separate phase segregates at the nanowire-SiO₂ interface provided that no special treatments were performed. This undesirable phenomenon was avoided by a special whisker treatment before oxidation.

Nanoobjects of interpolymer complex of polyaniline (PAn) and polysulfonic acid have been synthesized. The matrix chemical synthesis of PAn was carried out in aqueous solution at room temperature in the presence of poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) as a matrix. The choice of PAMPSA was determined by its good solubility in water, perfect film-forming properties and high molecular weight (∼ 2000000). The polymerization process of aniline on PAMPSA took place at pH ∼ 2 on the polymer backbone at high rate, while aniline concentration was sufficiently low. The true solution of PAn-PAMPSA interpolymer complex was coated on mica substrates. We have studied PAn films surfaces using FEMTOSCAN atomic force microscope (AFM) in dependence on the solution concentrations and the presence of strong electrolyte (HCl).

Refractive elements like lenses and prisms for surface plasmons with predefined effective refractive index were realized by thin-film elements. We demonstrate that the straightforward approach of using topographically structured dielectric coatings like polymethylmetacrylate can be successfully applied. The preparation process can thus be greatly simplified with respect to conventional approaches. The effective refractive index for plasmons is deduced in dependence on the film thickness. The value obtained is verified by SNOM imaging of refraction on prisms. Apart from common refraction, some plasmon-specific effects were observed and explained by finite element simulations.

Ultra-thin layers of aluminum oxide (less than 1 nm) were grown by atomic layer deposition (ALD) technique on hydrogen-terminated silicon substrates. A new technique, called ''plasma defect etching'', was proposed for the continuity evaluation of such a layer. The layer was examined by using it as a mask in silicon etching at cryogenic temperatures in a DRIE reactor. The etch profile was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Island formation during initial cycles was confirmed. Thicker aluminum oxide layers (1-5 nm thick) were patterned by wet or dry (plasma) etching and used as a mask for deep silicon etching at cryogenic temperatures in a DRIE reactor, using SF₆ and O₂ gas mixture. We found aluminum oxide to be an extremely resistant mask, etched only 0.05 nm/min. The value for the Si to Al₂O₃ selectivity reached 70 000:1.

Tubulin, a protein isolated from eukaryotic cells, is able to self-assemble in vitro under well-defined chemical conditions into highly ordered polymorphic suprastructures such as tubules, rings or sheets. Here we report about the imaging and the morphological appearance of such tubulin assemblies utilized as templates for the deposition of metal nanoparticles or continuous metallization. The structural imaging and analyzing tools like field emission scanning electron microscopy (FESEM) with respect to different electron detectors (Inlens-SE, BSE, TE) are addressed. An EDX-unit is applied for the verification of the deposited metals. Atomic force microscopy (AFM) in tapping-mode (TM) is adopted for 3D-rendering and morphological measurements (height). Tip-surface interactions, the influence of fixation and cantilever-types are considered. Transmission electron microscopy (TEM) is applied to visualize deposited nanoparticles.

In this study, the STM was used to locally study the adsorption of NO on a Rh(111) single crystal. Three new structures were identified. At 200 K, patches of the (4 × 2)-2NO and an unreported (2 × 2)-2NO structure were found at about 0.50ML coverage. Higher exposure gave rise to a (2 × 2)-3NO structure with all molecules adsorbed in the hcp sites. At 5K, a (4 × 4)-1NO structure was observed. The large separation between the molecules can only arise from repulsive interactions over a distance of at least four times the lattice constant (11 Å). Here the interaction is estimated to be of the order of ∼10K or ∼0.1 kJ/mol. Dynamic Monte Carlo simulations taking into account adsorption, diffusion and pairwise interactions between adsorbates were used to fit the lateral interaction for the next-next nearest neighbor to the patched STM topograph at 200K for 0.50ML coverage. The value was determined to be 2 kJ/mol. Using pairwise interactions only, the (2 × 2)-3NO structure could not be explained. It might therefore be necessary to include three-particle interactions. Recent DFT calculations support this idea by showing attractive three-particle interactions.

Useful information about the surface pore structure of polymeric track and Millipore membranes chosen as biosensor carriers have been obtained using the easyScan dynamic force microscope

A new controlled atmosphere high temperature SPM has been designed and build for the purpose of performing electrochemical measurements on solid oxide fuel cell materials. The first tests show that images can be obtained at a surface temperature of 465°C in air with a standard AFM AC probe. The aim is to produce images at a surface temperature of 800°C with electrically conducting ceramic probes as working electrodes that can be positioned at desired locations at the surface for electrochemical measurements.

Morphological variations of copper nanoparticles synthesized by the reduction of copper acetate with sodium borohydride in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) have been investigated. The results indicate that the specific rod shape secondary aggregation of copper nanoparticles are formed in the case that the oxygen is dissolved in the reacting solutions. Furthermore, it is also demonstrated that the copper nanorods with the aspect ratio of 2 - 20 and the average short axis length of 5 nm are synthesized in the weak oxidizing ambiance with a medium amount of PVP. The anomalous variations of copper nanoparticles are explained by the alignments of precursor copper ions and their reducing rates, which are modified by the density of resolved oxygen and the amount of PVP.

Using scanning tunneling spectroscopy at 5K electrostatic potential profile on the Si(111) √3x √3 Ag surface has been obtained with high spatial and energy resolutions. The potential profile measured around a step edge was explained with the Coulomb potential screened by a two-dimensional electron system which intrinsically exists on the surface. Friedel oscillation, which is characteristic to the screening, was also observed in the potential images. Its shape and phase were discussed in comparison with those of standing waves.

Thin iron silicide films were grown by solid phase epitaxy method on Si(111) surface. Silicide structure and magnetic properties at 40 K were observed with reflection high-energy electron diffraction and surface magneto-optic Kerr effect in-situ. The bcc-Fe film was grown at 40 K and transformed to polycrystals at 670 K annealing. The SMOKE revealed ferromagnetic property of the polycrystals at 40 K. After 820 K annealing, a β-FeSi₂ film was formed. This sample was ferromagnetic at 40 K. We suggest a multilayer structure including a ferromagnetic interface between the β-FeSi₂ film and the Si(111) substrate.

We observed three-dimensional (3D) elongated islands of iron silicide grown on Si(001) surfaces by solid phase epitaxy. Scanning tunneling microscopy images showed islands of narrow width (less than ≈3 nm) elongated to either Si[110] or Si[10] direction for 10–20 nm. Reflection high-energy electron diffraction patterns showed the transmission spots of the islands having reciprocal rods parallel to the surface, Si[10] and Si[110]. We proposed two possible crystal models, α-FeSi₂ and B2 (CsCl) FeSi, for the 3D elongated islands.

The relaxation rate of phonon modes in the (10, 10) single wall carbon nanotube undergoing three-phonon interactions at various temperatures has been studied using both qualitative and quantitative approaches based upon Fermi's Golden Rule and a quasi-elastic continuum model for the anharmonic potential. For the quantitative calculations, dispersion relations for the phonon modes were obtained from analytic expressions developed by Zhang et al. The qualitative expressions were derived using simple linear phonon dispersions relations. We show that in the high temperature regime the relaxation rate varies linearly with temperature and with the square of the frequency. In the low temperature regime we show that the relaxation rate varies exponentially with the inverse of temperature. These results have some very interesting implifications for effects for mean free path and thermal conductivity calculations.

We develop a first-principles calculation method for the quantum transport through nanostructures between electrodes by using the recursion-transfer-matrix (RTM) method combined with the nonequilibrium Green function (NEGF) method. This RTM/NEGF method is applied to the electronic states and current-voltage (I-V) characteristics of atomic-scale nanocontact system with and without nanosystems (single molecules) between electrodes. We observe similar non-linear behaviors in the I-V characteristics in various contact conditions. Such non-linear behaviors of I-V characteristics are determined not only by the electronic states of nanosystems between electrodes but also by the atomic-scale contact conditions. We find that the transitions from tunneling to ballistic regimes affect the I-V characteristics significantly.

We have studied a possibility to form nanometer-sized optical probe using prototype atomic force cantilevered SNOM and some fine structure samples. The system has an ability to obtain both atomic force microscope (AFM) and scanning near-field microscope (SNOM) images simultaneously. The fine optical probe was studied using the outside and inside Au coated SNOM probe. As experimental results, we have obtained a 10 nm-sized optical probe by observations of magneto-optical (MO) disc and Au thin film with many fine cracks.

Nitrogen-doped amorphous silicon carbide films were grown by a plasma enhanced chemical vapour deposition (PE CVD) technique. The actual amount of nitrogen in the SiC films is determined by Rutherford backscattering spectrometry (RBS). For irradiation experiments we use electron beams with a kinetic energy 200 keV, a pulse duration of 300 ns, and a beam current of 150 A/cm². It is found that with increased nitrogen doping and following activation of dopants the resistivity of the amorphous SiC films is substantially reduced.

Nanocrystalline NiO thin films were deposited by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Au on a NiO film surface. Very thin Au overlayers with a thickness of about 1 and 7 nm have been prepared by magnetron sputtering. Then, the surface modified NiO films have been analysed by TEM, EDX and SEM. NiO thin films showed a polycrystalline structure with the size of nanocrystals ranging from a few nanometers to 10 nm. Electrical responses of NiO-based structure towards hydrogen have been measured.

The optical responses of Au nanoparticle arrays dispersed within porous anodic alumina (PAA) have been investigated. The 2D Au/PAA structures were well preparing by immersing various pore sizes of PAAs into the mixing solution of HAuCl₄, cetyl-trimethyl ammonium bromide, and NaBH₄ under Au phase transfer processes. With the dispersion of Au nanoparticles in those nanopores in PAA, the intensity of photoluminescence light and cathodoluminescence light spectra largely decreases. The dissipated emission could be interpreted by the partly sealing of the light emission oxygen defect centers in PAA with the dispersion of Au nanoparticles. The major absorption comes from the interface plasmon resonance of Au nanoparticles surrounding with PAAs. The excited Au nanoparticles act as a Bragg grating for wave propagation scattering into the alumina matrix.

Silver nanoparticles have drawn extensive attention as biomaterial components. Human fibroblasts were grown on various concentrations of silver nanoparticles during the period observation. Normal viability (0% silver particles) was increased from 6 to 72 hours, increasing the amount of human fibroblasts (1.5 × 10⁴ to 7 × 10⁶ cells/well) normally. Nevertheless, at higher concentrations of silver nanoparticles (50%) 1.11 × 105 cells/well remained after 72 hours. Results indicated that the increase in the concentration of silver nanoparticles reduced the number of fibroblasts and affected their fission. Silver nanoparticles were found under the membranes of fibroblast following dry treatment. The number of tissues declined because the silver nanoparticles interrupted the fission mechanism during their development in vivo.

In diseases such as cancer or during viral infections gene expression is greatly altered. These changes in gene activity can be analysed at different levels of cellular activity, like transcription activation, transcription and translation. Currently, no simple method is available to detect all these biochemical signals simultaneously and rapidly. Micromechanical cantilever sensor array technology is applied, because it has the advantage that sample preconditioning like labelling and amplification is not required. Furthermore, DNA, RNA, protein or combinations thereof could be detected in parallel on a single cantilever array. With such a device, diagnosis and therefore treatment of diseases can be improved. Here we present successive detection of DNA hybridization and antigen using the same micromechanical cantilever sensor array.

We report the first cut of our study on the behavior of a plasmon excitation observed from quasi-one-dimensional (Q1D) metallic nanowires self-assembled on the Si(111) surface. We have utilized a high-resolution electron-energy-loss spectroscopy to measure the extremely anisotropic dispersions of the Q1D plasmon excitation. The energy-momentum dispersion w(q) is well accounted by both theories with and without interactions, and thus provides no evidence for non-Fermi liquid properties. The q-dependence of life time of the plasmon, however, seems to exhibit a behavior distinct from that of Fermi liquid as predicted recently.

DNA self-assembly is a powerful route to the production of very small, complex structures. When used in combination with nanoparticles it is likely to become a key technology in the production of nanoelectronics in the future. Previously, demonstrated nanoparticle assemblies have mainly been periodic and highly symmetric arrays, unsuited as building blocks for any complex circuits. With the invention of DNA-scaffolded origami reported earlier this year (Rothemund P W K 2006 Nature440 (7082) 297–302), a new route to complex nanostructures using DNA has been opened. Here, we give a short review of the field and present the current status of our experiments were DNA origami is used in conjunction with nanoparticles. Gold nanoparticles are functionalized with thiolated single stranded DNA. Strands that are complementary to the gold particle strands can be positioned on the self-assembled DNA-structure in arbitrary patterns. This property should allow an accurate positioning of the particles by letting them hybridize on the lattice. We report on our recent experiments on this system and discuss open problems and future applications.

We fabricated a pair of nano-gap electrodes to contact an uncapped single selfassembled InAs quantum dot and studied the single-electron transport properties. We observed clear signatures of the Kondo effect as the temperature was lowered, such as lifting of a Coulomb valley corresponding to an odd number of electrons in the dot and zero-bias anomaly in the differential conductance in the Coulomb valley. From the temperature dependence of these features, we estimated the Kondo temperature of about 2 K.

Osteoarthritis is a painful and disabling progressive joint disease, characterized by degradation of articular cartilage. In order to study this disease at early stages, we have miniaturized and integrated a complete scanning force microscope into a standard arthroscopic device fitting through a standard orthopedic canula. This instrument will allow orthopedic surgeons to measure the mechanical properties of articular cartilage at the nanometer and micrometer scale in-vivo during a standard arthroscopy. An orthopedic surgeon assessed the handling of the instrument. First measurements of the elasticity-modulus of human cartilage were recorded in a cadaver knee non minimal invasive. Second, minimally invasive experiments were performed using arthroscopic instruments. Load-displacement curves were successfully recorded.

The structural (Raman spectroscopy), electrical (Current-Voltage analysis) and photoelectrical (Photoconduction analysis) properties of the tungsten trioxide films annealed in air at different temperature are reported. The influence of the thermal post-treatment on the morphology of the films and the role of oxygen vacancies on the WO₃opto-electronic properties has been discussed and linked with possible applications in hydrogen production in a PECC.

Thin films of CuS (covellite) were deposited onto TCO (SnO₂:F) glass by Spray Pyrolysis (SP) technique. Aqueous and water:alcohol (ethanol, 1-propanol) solutions of copper(II) chloride and thiourea with different Cu/S molar ratio have been used as precursors. The substrate temperature was varied from 185 °C to 285 °C. The structural and the morphological characterization of the films has been carried out by Raman spectroscopy and Scanning Electron Microscopy. The X-Ray Diffraction analysis of as-grown films showed the single-phase covellite, with hexagonal crystal structure built around three preferred orientations corresponding to (102), (103) and (110) atomic planes. The dense morphology of CuS films with large crystallites/aggregates suggest that crystal growth is the limiting step in the films deposition, at 235 °C and at 285 °C, from precursors' solution containing water or mixtures of water:alcohol as solvents. The growth of CuS thin films by spray pyrolysis is favored by increasing both the alcohol concentration and the deposition temperature.

A new, facile and straightforward method for synthesis of ligands possessing multiple binding sites is reported. The reaction pathway involve acylation of -halogenated dihydroxyacetophenone followed by quaternisation with nitrogen heterocycles. A new class of oxa- and oxaaza- coronands was obtained.

A fast, efficient and general method for preparation of highly fluorescent derivatives containing pyrrolodiazine moiety using microwave is reported. The aromatised pyrrolopyridazine are very intense blue emitters and the quantum yields are very high.

The general intention of this work is to analyze spatially and temporally variable nanostructured surfaces generated by functionalized magnetic beads on a biocompatible carrier substrate to induce cell differentiation. Magnetic thin films with particular domain structures are used to align magnetic nanobeads of around 250nm diameter (Fe₃O₄ core) by means of magnetic interaction. The beads' properties are investigated by atomic force microscopy (AFM) and magnetic force microscopy (MFM), respectivly. As the magnetic substrates as well as the beads are biocompatible the set up is used as a substrate for cell growth. AFM gives information about the cells' behavior on the artificial structures. By using external magnetic fields in the range of 10mT the magnetic structure of the thin films can easily be modified in vivo which gives the opportunity to study the influence of structured substrates not only with respect to topographical but also to dynamical changes.

Cadmium sulfide (CdS) nanoparticle (NP) was synthesized in the apoferritin cavity by slow chemical reaction system (SCRY) and two step synthesis protocol (TSSP). The survey showed thioacetic acid as the optimum sulfur source to form CdS NPs in the apoferirin cavity. Thioacetic acid degrades slowly in weak acidic solution and releases the sulfide ions continuously for long period. The synthesized NP was determined as CdS in cubic phase by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction measurement (XRD). Semiconductor CdS NP surrounded by protein shell can disperse in aqueous solution and will be able to be applied to nano-electronic devices or fluorescent biomarker.

A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. By considering the covalent bonds as connecting elements between carbon atoms, a nanotube is simulated as a space frame-like structure. Here, the carbon atoms act as joints of the connecting elements. To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. Using Morse atomic potential, the elastic moduli of beam elements are obtained via considering a linkage between molecular and continuum mechanics. Also, a new wall thickness ( = bond diameter) equal to 0.1296 nm is introduced. In order to demonstrate the applicability of FE model and new wall thickness, the influence of tube wall thickness, diameter and chirality on the Young's modulus of SWCNTs is investigated. It is found that the choice of wall thickness significantly affects the calculation of Young's modulus. For the values of wall thickness used in the literature, the Young's moduli are estimated which agree very well with the corresponding theoretical results and experimental measurements. We also investigate the dependence of elastic moduli on diameter and chirality of the nanotube. The larger tube diameter, the higher Young's modulus of SWCNT. The Young's modulus of chiral SWCNTs is found to be generally larger than that of armchair and zigzag SWCNTs. The presented results demonstrate that the proposed FE model and wall thickness may provide a valuable tool for studying the mechanical behavior of carbon nanotubes and their application in nano-composites.

Detection of the cytoplasmic domain of transmembrane oncoproteins attracts primary attention in cancer diagnosis, since the diagnostically marked extracellar domain is shed off along with increased malignancy. The shedding problem severely inhibits the conventional cell diagnosis, like immunomicroscopy from outside the cells. If detection on the cytoplasmic surface of each cell membrane becomes as extensive as the detection on the whole cell membrane and as efficient as that done within seconds, it will be in high demand. We propose here a new application of femtosecond laser, where a single cell is ruptured as a laserinduced cavity expands in cytosol and the whole cell membrane is thus projected over a flat surface in a short period of time (< 10 s). Using this configuration, we achieved projection of the cytoplasmic surface of the cell membrane for 57% of murine erythroleukemia cells irradiated, including 34% of them at full extension of the membrane. The inside-out projection was confirmed by immunostaining both -actinin in murine erythroleukemia cells and an oncoprotein c-erbB2 in human adenocarinoma cells. This projection requires only a small area (< 1000 μm²) and a short irradiation interval on a microscope slide, thus leaves room for a high throughput serial process.

Thermal stability of silver ions in silicate glasses in dry and wet (0.5 - 50% of water content) atmosphere under elevated (160–230 °C) temperature is studied. The glass is doped with silver using silver-to-sodium ion exchange procedure conventionally used for the formation of optical waveguides. It is found that the isothermal annealing of glasses doped with Ag⁺ ions in a wet argon atmosphere leads to the reduction of silver to metallic state and to the formation of silver nanoclusters in the glass body. The clustering in the course of water diffusion into the glass was studied by optical spectrometry. The clusters were not formed during annealing in a dry atmosphere at the same temperatures.

The laser-induced acceleration of nanoparticles using intense light irradiation was used for positioning and ordering of carbon nanomaterials to form periodical surface structures. Such systems are of interest for different nanotechnology applications. The nanodiamond with averaged size 100 nm, and fullerene (C₆₀) suspended in distilled water were accelerated using high focused laser beam and attached onto metal surface of silver and gold thin films evaporated on Si substrate. The laser was operating both in CW and femtosecond modes with the wavelength of ∼800 nm, pulse duration 150 fs, and average laser power of 300-600 mW. In case of pulse irradiation the repetition rate of 76 MHZ was applied. The nanoparticles were positioned on the metal surface in accordance with a predetermined program to allow patterning of the nanoparticles. The positioning was analyzed for different treatment conditions and compared to the calculated data. To investigate the obtained nanoparticles/metal structures, surface-enhanced Raman scattering (SERS) was used utilizing its high sensitivity on the local properties of the nanostructures. SERS allows the observing of carbon nanostructures with their characteristic peculiarities, such as blinking effect and selective enhancement. Here we try to explain the spectral and spatial peculiarities occurring during the laser acceleration process and the interaction of attached carbon nanostructures with metal surface.

An electrochemical anodization technique associated with wet surface cleansing processes was applied for fabrication of surface nanoscale structures on Al plates. Dynamic force microscopy (DFM) measurements clarifies that different wet cleansing processes create different initial surface structures on Al such as a linked-crater pattern and a groove-pattern on Al surfaces and induce finer and well-ordered characteristic surface nanoscale patterns. Based upon those structures, anodization proceeds in the fabrication of well-ordered characteristic nanoscale patterns on Al surface such as a well-oriented row-aligned pattern and a well-fined lattice pattern. Deposition of copper phthalocyanine (CuPc) molecules upon anodized craterarrayed Al surface is conducted by casting CuPc resolved toluene. DFM and X-ray photoemission spectroscopy (XPS) measurements clarify that an organic-inorganic nanoscale patterned material is fabricated.

This paper reports on synthesis of Ni-Co alloy films using electrodeposition technique. The morphology and crystalline characteristics of the films have demonstrated dependence on deposition parameters. The electrolyte temperature and pH have shown to have the most influence on the crystallographic structure of the film. The microstructure, crystallographic texture and magnetic properties are studied by varying the substrate pretreatment and deposition parameters. The dependence of the surface morphology has been investigated by employing SEM, XRD, EDAX and AFM. X-ray diffraction analyses have revealed the polycrystalline nature of the films, the average crystallite size, and the crystal orientation that has dependence on temperature and pH of the electrolyte. VSM analysis has revealed that the coercivity has also dependence on temperature and pH of the bath due to variation of crystal orientation and crystallite size of the films on copper substrates.

To investigate the surface roughness, and get some information about statistical behaviour of Cu thin films and knowledge about morphology and fractal characteristics of them, copper thin films have been deposited on glass substrate by dc magnetron sputtering method. In different deposition rate (0.4-2.5 nm/sec), effect of this parameter on surface roughness has been investigated. By AFM studies interface width (W or surface roughness) and structure function S₂(l) as well as different moment of structure function S_q(l) and correlation length also have been investigated for various experimental conditions. Fractal properties of them have been studied too and height distribution satisfied Gaussian distribution function.

X-ray photoelectron spectroscopy (XPS), X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) methods were used to study the electronic structure of hexagonal h-WO₃ and h-WO_2.8 nanoparticles. For comparison, nanopowder substoichiometric monoclinic tungsten oxides with close content of oxygen atoms, namely m-WO₃ and m-WO_2.77 compounds, were also investigated. For the mentioned oxides, XPS valence-band and corelevel spectra, XES O Kα bands and XAS W L_III and O 1s edges were derived. The XPS valence-band spectra and O Kα emission bands in the mentioned hexagonal and monoclinic tungsten oxides were compared on a common energy scale. Both the O Kα bands and XPS valence-band spectra broaden somewhat in the sequences h-WO₃ → h-WO_2.8 and m-WO₃ → m-WO_2.77, with the half-widths of the spectra being somewhat higher for the hexagonal oxides as compared with those for the monoclinic compounds. The effective positive charge state of tungsten atoms in h-WO_2.8 is very close to that in m-WO_2.77, but the negative charge states of oxygen atoms are close to each other for all the tungsten oxides under consideration.

The stress-related ferroelectric properties have been studied on the Triglycine sulfate (TGS) by scanning probe microscope (SPM). Together with normal stress of the tip, the lateral stress is applied to the sample with piezoelectric transducers. With this study, we characterized the way the ferroelectricity of TGS responds to the axis-specific stress. Specially, the b-directional stress applicable to the surface can amount to several GPa such that the polarization switching by mechanical stress is observable. Although the lateral stress is not strong enough to view such phenomena, a-axis(c-axis) stress still affects the polarization value so as to fortify (lessen) the electric field inside, respectively. These contrasting results can be explained by the sign relation of piezo-coefficients about the individual axis. This work can be a touchstone of future researches in characterizing the elelctromechanical properties of more popular ferroelectrics such as PZT or BTO.

Lead-free piezoceramics Bi_0.5(Na_1-xK_x)_0.5TiO₃ (x = 0.00∼1.00) has been investigated by using scanning probe microscope with lock-in technique. Superior to other bulk measurements, this technique gives not only the topological but the piezo/ferroelectric properties without any convolutions. By the appropriate selection of lock-in channel and spectra analysis, we can get the trend of the magnitude and phase of polarization with different x value. And this enables us to find the morphotropic phase boundary successfully.

We describe a novel method of scanning probe nanofabrication using an AFM(atomic force microscopy) tip with assistance of femtosecond laser pulses to enhance fabrication capability. Illuminating the AFM tip with ultra short light pulses induces a strong electric field between the tip and the metal surface to be fabricated. The optically generated electric field permits removing metal atoms from the surface by means of field evaporation with an improved level of controllability on the atom transfer direction and rate in comparison to customary manipulation based on intrinsic chemical interactions between atoms. Simulation performed in this investigation reveals that the optical field evaporation is triggered even in air when the induced electric field reaches a few volts per nanometer. Experimental results demonstrate that fine structures with critical dimensions less than ∼10 nm can be successfully made by precise controlling femtosecond laser pulses.

Recent outbreaks of foodborne illness have been increased the need for rapid and sensitive methods for detection of these pathogens. Conventional methods for pathogens detection and identification involve prolonged multiple enrichment steps. Even though some immunological rapid assays are available, these assays still need enrichment steps result in delayed detection. Biosensors have shown great potential for rapid detection of foodborne pathogens. They are capable of direct monitoring the antigen-antibody reactions in real time. Among the biosensors, impedimetric biosensors have been widely adapted as an analysis tool for the study of various biological binding reactions because of their high sensitivity and reagentless operation. In this study a nanoparticle-enhanced impedimetric biosensor for Salmonella enteritidis detection was developed which detected impedance changes caused by the attachment of the cells to the anti-Salmonella antibodies immobilized on interdigitated gold electrodes. Successive immobilization of neutravidin followed by anti-Salmonella antibodies was performed to the sensing area to create a biological detection surface. To enhance the impedance responses generated by antigen-antibody reactions, anti-Salmonella antibody conjugated nanoparticles were introduced on the sensing area. Using a portable impedance analyzer, the impedance across the interdigital electrodes was measured after the series of antigen-antibody bindings. Bacteria cells present in solution attached to capture antibodies and became tethered to the sensor surface. Attached bacteria cells changed the dielectric constant of the media between the electrodes thereby causing a change in measured impedance. Optimum input frequency was determined by analyzing frequency characteristics of the biosensor over ranges of applied frequencies from 10 Hz to 400 Hz. At 100 Hz of input frequency, the biosensor was most sensitive to the changes of the bacteria concentration and this frequency was used for the detection experiments. The biosensor was able to detect 10⁶ CFU/mL in phosphate buffered saline (PBS) with a detection time of 3 minutes. Additional use of nanoparticles significantly enhanced the detection performance. By using the nanoparticles the biosensor could detect 10⁴ CFU/mL of Salmonella enteritidis in PBS and 10⁵ CFU/mL of cells in milk.

Various PDMS patterns with a few microns to sub-micron size and thickness of 20∼30 nanometers were successfully transferred on the substrate via simple printing process of a buffered oxide etchant-treated PDMS stamp on the SiO₂ substrate. The patterned PDMS layer acted as sacrificial layer for metal-film patterning and as chemical passivation layer for the selective adsorption of V₂O₅ nanowires. In particular, the electrical measurement of the patterned V₂O₅ nanowire network showed the semiconducting non-ohmic behavior in the channel.

We investigate the carrier injection and transport in individual para-hexaphenylene nanofibers by electrical transport measurements at different temperatures. The injected current shows much weaker temperature dependence than what would be anticipated from a simplistic model that considers the injection barrier height equal to the difference between the metal electrode work function and the HOMO energy level of the organic semiconductor. Semiquantitative modeling suggests that the weak temperature dependence is due to injection into a distribution of states rather than into a single energy level. This disorder induced energy level broadening could be caused by the electrode deposition process.

In this article results of complete modelling of electromagnetic field distribution in a near-field scanning probe microscope (NSOM) are presented. It is shown, that using finite difference in time domain method the NSOM signal can be computed for real tip-sample geometry. The results of such a simulation can be used to predict presence and distribution of topography related artefacts in NSOM images.

In this article the results of atomic force microscopy (AFM) and scaning thermal microscopy (SThM) of delaminated thin films are presented. It is shown that SThM data can be used for a very precise localisation of the delaminated areas that is necessary for the analysis of film material properties. Moreover, by using AFM it is also possible to characterize morphology of the blister upper boundary with a high resolution too. The quantitative results obtained by the above mentioned methods are compared with nanoindentation measurements.

A previous method proposed for gold deposition on silica spheres (Kobayashi et al., 2005) was extended to uniform deposition of Au nanoparticles on submicron-sized polystyrene spheres. This method consisted of surface-modification and elecroless Au plating. The chemical agents examined for the surface-modification were sodium persulfate, 3- aminopropyltrimethoxysilane, polyelectrolytes and polyvinylpyrrolidone. The elecroless Au plating included three steps: (1) the adsorption of Sn²⁺ ions took place on surface of silica particles, (2) Ag⁺ ions added were reduced and simultaneously adsorbed to the surface, while Sn²⁺ oxidized to Sn⁴⁺, and (3) Au⁺ ions added were reduced and deposited on the Ag surface. TEM observation revealed that Au nanoparticles with sizes of 8-25 nm were uniformly deposited on the polystyrene spheres that were modified with polyvinylpyrrolidone. The Au nanoparticle deposition was confirmed by UV-VIS absorption spectroscopy.

This paper presents a new quantitative method that evaluates the cell attachment affinity to aligned scaffold structures composed of poly (glycolic acid) PGA/collagen. The structures were fabricated by the electrospinning method. We analyzed the relationship between the number and length of attached cells to fibers of different diameters under different concentrations of PGA/collagen. The findings are three fold. Firstly, the fibers fabricated on the order of nano-scale significantly enhanced the number of attaching cells compared with those fibers fabricated on the order of micro-scale. Secondly, the cell morphology is affected by both the amount of collagen in PGA/collagen hybrid fibers and the cells adhesion affinity to fibers. Finally, PGA/collagen hybrid fibers on the range of 0.5 μm with a concentration of 67% collagen provided the best cell adhesion. This study provides an attractive technique to fabricate suitable diameters and collagen concentrations for tissue engineering applications.

To optimize the performance of the high-frequency magnetic force microscopy (HFMFM) technique, we investigate the effect of varying the frequency of the amplitude modulation on the magnetic contrast achieved. As samples, we employ hard disk writer poles. We find that the optimum condition for the HF-MFM operation is the use of a modulation frequency being about half of the cantilever resonant frequency. Together with optimized cantilevers, a clear improvement of the magnetic imaging is obtained. Furthermore, we can deduce that the optimum parameters for imaging must be determined for each experimental system (hard disk writer pole and cantilever) individually.

To optimize the performance of the high-frequency MFM (HF-MFM) technique [1-4], we performed a search for the best suited cantilever type and magnetic material coating. Using a HF-MFM setup with hard disk writer poles as test samples, we carried out HF-MFM imaging at frequencies up to 2 GHz. For HF-MFM, it is an essential ingredient that the tip material can follow the fast switching of the high-frequency fields. In this contribution, we investigated 6 different types of cantilevers, (i) the ''standard'' MFM tip (Nanoworld Pointprobe) with 30 nm CoCr coating, (ii) a ''SSS'' (Nanoworld SuperSharpSilicon^TM) cantilever with a 10 nm CoCr coating, (iii) a (Ni, Zn)-ferrite coated pointprobe tip, (iv) a Ba₃Co₂Fe₂₃O₄₁ (BCFO) coated pointprobe tip, (v) a low-coercivity NiCo alloy coated tip, and (vi) a permalloy-coated tip.

Topographic investigations of surfaces of melt-textured GdBa₂Cu₃O_x (GdBCO) samples were performed by means of AFM and STM at ambient conditions. Pure GdBCO is found to exhibit mainly nanoclusters, while GdBCO doped with ZnO nanoparticles reveals the nanostripe patterns as observed earlier in other high-T_c cuprates. Details of the nanostripe patterns are investigated. Using the electron backscatter diffraction technique and polarization microscopy, we could determine the crystallographic orientation of the nanostripes and their interaction with the always present twin boundary structure.

Since the discovery of its superconductivity (J. Nagamatsu, N. Nakagawa, T. Muranka, et al., 2001, Nature, 410, 63), MgB₂ attracts considerable attention. A number of groups have intensively tried to fabricate high-quality MgB₂ films during the last years. However, the surface quality which is necessary for microelectronic device applications is still far from being achieved In this work we report the growth and the properties of high-quality films which are prepared in a two-step process: 1) deposition of the precursor films and 2) their annealing in Mg vapor with a specially designed, reusable reactor (C. B. Eom, et al., 2001, Nature, 411, 558). The films were grown on single crystal substrates of R-cut Al₂O₃ as well as of Al₂O₃ (100), (128° rot) LiNbO₃ and MgO (100). The highest value of T_c = 39.4 K was observed for films deposited at 770 K on sapphire and MgO and annealed at 1120 K for one hour. Our method allows also the growth of high-T_c smooth films with high reproducibility and opens perspectives for the use of MgB₂ films in microelectronics, especially for high-frequency applications.

Cantilever sensors have created a widespread interest in recent years due to their unique nanomechanical signal generation mechanism. Their applications range from sensing of small molecules, chemicals and biomolecules to on-line monitoring of surface-associated phenomena, such as molecular reorganization and formation of self assembled monolayers (SAMs). Cantilever sensors allow real-time monitoring, which is the basis for the kinetic description of interactions at the sensor surface. In this paper, we present examples of cantilever sensor measurements in continuous liquid flow using a commercially available instrument (Cantisens® Research, Concentris GmbH, Switzerland) and demonstrate successful approaches for

a) the description of molecular interaction kinetics,

b) the improvement of calibration curves of cantilever biosensors and

c) the study of SAM formation, protein immobilization and surface-related conformational changes.

We report the enhancement of the nonlinear optical response of the weakly confined excitons with use of spectrally rectangular pulse. The nonlinear optical response was investigated as a function of excitation energy by a degenerate four-wave-mixing (DFWM) technique. In the case that the laser pulse with the controlled spectral shape excites the plural exciton states simultaneously, the DFWM signal intensity is enhanced by a factor of two in comparison with the intensity under the excitation of a single exciton state. This enhancement is caused by the superposition of the nonlinear optical responses from the plural exciton states.

Scanning tunnelling microscopic studies have been performed to study the 2D structuring of the inorganic salt, the Keggin-type [AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺ in its sulfate form. This compound forms patches of well ordered monolayer separated by defects seen on large scan images on the top of highly oriented pyrolitic graphite surface. A negative differential resistance peak has been found by scanning tunnelling spectroscopy. Surfactant molecules self-assemble horizontally in the first layer on the graphite plane. Higher uptake resulted in the formation of hemicylinders. In this study sodium dodecyl sulfate has been used to modify the 2D Keggin arrangements. By this combination of organic and inorganic materials the large counter ions were expected to re-arrange on the surface. In this surfactant assisted artificial ordering the distance between the Keggin-type units has been increased.

Due to their extreme aspect ratios and exceptional mechanical properties Carbon Nanotubes terminated silicon probes have proven to be the ''ideal'' probe for Atomic Force Microscopy. But especially for the manufacturing and use of Single Walled Carbon Nanotubes there are serious problems, which have not been solved until today. Here, Single and Double Wall Carbon Nanotubes, batch processed and used as deposited by Chemical Vapor Deposition without any postprocessing, are compared to standard and high resolution silicon probes concerning resolution, scanning speed and lifetime behavior.

We have investigated the interaction between an Fe atom and a single-walled carbon nanotube near the entrance, by means of the first principles total energy calculation. (10, 0) carbon nanotube composed of 80 atoms is used for the calculation. We determined the most stable position of the Fe atom near the entrance of the nanotube.

We investigated the influence of Mn and Mg co-implantation accompanied by rapid thermal annealing on magnetic and galvanomagnetic properties of p-GaAs. We characterized the samples with SQUID magnetometry and magnetotransport measurements in the temperature interval 4.2 K<T<400 K. Magnetization measurements reveal ferromagnetism up to 400 K (limited by the experimental setup) in all implanted samples. Temperature dependences of resistance, magnetoresistance and Hall effect have been measured in the temperature range 4.2⩽T⩽300 K. The anomalous Hall effect is visible up to 195 K and shows influence of ferromagnetism of Ga_1-xMn_xAs solid solution on galvanomagnetic properties of holes. Above this temperature, ferromagnetism survives due to the MnAs and Ga_1-xMn_x clusters. The magnetoresistance changes from colossal negative to enhanced positive with increasing temperature near T = 35 K.

High-purity carbon nanotubes (CNTs) are produced by chemical vapour deposition of camphor, an environment-friendly hydrocarbon. In a small CVD reactor (1-m long and 26- mm wide), CVD of 3 g camphor at 650°C for 1 hour yields ∼1.62 g MWNTs of diameter ∼10 nm with an as-grown purity over 88%; that is, camphor-to-CNT production efficiency is 50%. This is the highest efficiency ever achieved from any material by any method. Moreover, camphor-based CNT synthesis technique stands fairly good against the 12-principle protocol of green chemistry.

We use Ballistic Electron Emission Microscopy (BEEM) technique to determine directly the Schottky barrier distribution over silver /H-T₃-(CH₂)₄-HS (abbreviated as T3C4SH) self assembled monolayer interface area with nanometer scale spatial resolution. The selfassembled monolayer is absorbed on template stripped gold. BEEM images show spatially non-uniform carrier injection. A Wentzel Kramel Brillouin (WKB) calculation is performed and compared with BEEM spectra. The results show that the measured currents are four orders of magnitude larger than the direct tunnelling contribution, indicating molecular levels being accessed. To further substantiate the findings, characterization by STM distance versus potential spectroscopy is carried out to determine injection barriers at the interface. The results from these two techniques are compared and the implications of which will be discussed.

Very thin, crystalline semiconductor membranes represent a new nanosystem with very high potential for both technology and novel science. This article reviews aspects of the fabrication and properties of silicon-based nanomembranes and nanowires, including processing, strain engineering, and electronic transport. Particular emphasis is on elastic strain sharing, in which significantly strained single-crystal sheets or novel nanoshapes can be made.

The biological sensitivity of a DNA chip depends on the molecular organization of the immobilized probe molecules, single stranded DNA (ss-DNA), on the substrate in terms of accessibility and non specific interactions between probes and substrate. In this article, Amplitude Modulation - Atomic Force Microscopy (AM-AFM) was used to characterize at a molecular scale, the morphological organization of different immobilized probes. In our system, three different ss-DNA were covalently grafted on a silicon substrate with the same deposit process. We studied the influence of probe length (25 bases, 12 bases) and sequence arrangement (two different 25 base oligoprobes) on the morphological organization. We showed that immobilized probes organize themselves in different structures depending on their sequence.

We used microfabricated cantilever array sensors for an artificial nose setup. Each cantilever is coated on its top surface with a polymer layer. Volatile gaseous analytes are detected by tracking the diffusion process of the molecules into the polymer layers, resulting in swelling of the polymer layers and therewith bending of the cantilevers. From the bending pattern of all cantilevers in the array, a characteristic 'fingerprint' of the analyte is obtained, which is evaluated using principal component analysis. In a flow of dry nitrogen gas, the bending of the cantilevers is reverted to its initial state before exposure to the analyte, which allows reversible and reproducible operation of the sensor. We show examples of detection of solvents, perfume essences and beverage flavors. In a medical application, the setup provides indication of presence of diseases in patient's breath samples.

Massively Parallel Scanning Probe Microscopy is an obvious path for data storage (E Grochowski, R F Hoyt, Future Trends in Hard disc Drives, IEEE Trans. Magn. 1996, 32, 1850- 1854; J L Griffin, S W Schlosser, G R Ganger and D F Nagle, Modeling and Performance of MEMS-Based Storage Devices, Proc. ACM SIGMETRICS, 2000). Current experimental systems still lay far behind Hard Disc Drive (HDD) or Digital Video Disk (DVD), be it in access speed, data throughput, storage density or cost per bit. This paper presents an entirely new approach with the promise to break several of these barriers. The key idea is readout of a Scanning Probes Microscope (SPM) array by Digital Holographic Microscopy (DHM). This technology directly gives phase information at each pixel of a CCD array. This means that no contact line to each individual SPM probes is needed. The data is directly available in parallel form. Moreover, the optical setup needs in principle no expensive components, optical (or, to a large extent, mechanical) imperfections being compensated in the signal processing, i.e. in electronics. This gives the system the potential for a low cost device with fast Terabit readout capability.

An integrated method using field-emission to control the tip-sample distance for non-contact magnetic probe recording is presented, adopting the exponential relation between current and electric field as feedback. I/V characteristics that correspond well to field emission theory are measured using a probe coated with a 100 nm conductive diamond layer. By using feedback to control the tip-sample distance at constant current, the distance was increased by 2.8 nm per volt applied bias. The method was tested by scanning a probe coated with 20 nm chromium over a conducting nanopatterned sample, at bias voltages of 0.5V, 5.0V and 50.0V. The measurements confirm that field emission can be applied to control the tip-sample distance, with sufficient resolution and current stability for magnetic probe recording.

In this paper, the novel SPM (Scanning Probe Microscope) probe with the planar MOS (Metal-Oxide-Semiconductor) transistor and the FIB (Focused Ion Beam) nano tip is fabricated for the surface electric properties. Since the MOS transistor has high working frequency, the device can overcome the speed limitation of EFM (Electrostatic Force Microscope) system. The sensitivity is also high, and no bulky device such as lock-in-amplifier is required. Moreover, the nano tip with nanometer scale tip radius is fabricated with FIB system, and the resolution can be improved. Therefore, the probe can rapidly detect small localized electric properties with high sensitivity and high resolution. The MOS transistor is fabricated with the common semiconductor process, and the nano tip is grown by the FIB system. The planar structure of the MOS transistor makes the fabrication process easier, which is the advantage on the commercial production. Various electric signals are applied using the function generator, and the measured data represent the well-established electric properties of the device. It shows the promising aspect of the local surface electric property detection with high sensitivity and high resolution.

Transparent and conducting tin oxide fibers are of considerable interest for solar energy conversion, sensors and in various electrode applications. Appropriate doping can further enhance the conductivity of the fibers without loosing optical transparency. Undoped and antimony-doped tin oxide fibers have been synthesized by our group in previous work using electrospinning and metallorganic decomposition techniques. The undoped tin oxide fibers were obtained using a mixture of pure tin oxide sol made from tin (IV) chloride : water : propanol : isopropanol at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) and chloroform at a ratio of 200 mg PEO/10 mL chloroform. In this work, antimony doped fibers were obtained by adding a dopant solution of antimony trichloride and isopropanol at a ratio of 2.2812 g antimony trichloride/10 ml isopropanol to the original tin oxide precursor solution. The Sb concentration in the precursor solution is 1.5%. After deposition, the fibers were sintered 600°C in air for two hours. The electrical conductivity of single fibers measured at room temperature increases by up to three orders of magnitude when compared to undoped fibers prepared using the same method. The resistivity change as a function of the annealing temperature can be attributed to the thermally activated formation of a nearly stoichoimetric solid. The resistivity of the fibers changes monotonically with temperature from 714Ω-cm at 2 K to 0.1Ω-cm at 300 K. In the temperature range from 2 to 8 K the fibers have a positive magnetoresistance (MR) with the highest value of 155 % at 2 K and ±9 T. At temperatures of 10 and 12 K the sign of MR changes to negative values for low magnetic fields and positive for high magnetic fields. For higher temperatures (15 K and above) the MR becomes negative and its magnitude decreases with temperature.

Tin oxide is a binary semiconducting oxide with many applications in the development of sensors and optoelectronic devices. The recent advances in tin oxide micro/nano fibers fabrication have stimulated expectations for their applications due to their quasi-one dimensional morphology. The expectations may be limited by our ability to alter or modulate the electronic properties of the fibers. Based on our previous synthesis and characterization of electrospun tin oxide micro/nanofibers, the authors continued to investigate the electronic transport properties of single tin oxide fibers (belts) using the two probe method. Single tin oxide fibers were deposited onto silicon wafers with an oxidized surface layer of 150 nm in thickness with the electrodes for the electrical measurements made by evaporating silver over a metallic grid. I-V characteristics of single fibers were measured from 300 K down to 4 K in high vacuum with zero magnetic fields and with a transverse magnetic field that varied from −9 to 9 T. The fibers demonstrated a linear I-V characteristic in the range of −1 V and +1 V with its slope sensitive to the environment and temperature. The conductivity was found to decrease monotonically as the temperature decreases from 300 K. Above 8 K the electronic conduction mechanism corresponds to 3-dimensional Variable Range Hoping (VHR). A positive magnetoresistance of 110 % was found at 4 K and the mobility and carrier concentration for temperatures from 4 K to 15 K were on the range (0.2−1.2) cm²/V.s and (5.84×10¹⁸−6.91×10²⁰) cm⁻³, respectively.

We present enhanced second harmonic generation (SHG) from arrays of overlapping double holes in a gold film with varying angles of incidence. The double-hole structure permits enhanced SHG when the two holes are just overlapping to produces two sharp apexes. For different center-to-center hole spacings, the maximum occurs for different angles, which is attributed to a shift in the linear transmission wavelength peak of the array and to the requirement to break centrosymmetry for SHG.

Carbon materials are a class of significant and widely used engineering adsorbent. As a new member of the carbon family, carbon nanotubes have exhibited great potentials in applications as composite reinforcements, field emitters for flat panel display, sensors, energy storage and energy conversion devices, and catalysts support phases, because of their extraordinary mechanical, electrical, thermal and structural properties. In particular, the large specific surface areas, as well as the high chemical and thermal stabilities, make carbon nanotubes an attractive adsorbent in wastewater treatment. The adsorption properties of the carbon nanotubes to a series of toxic agents, such as lead, cadmium and 1, 2-dichlorobenzene have been studied and the results show that carbon nanotubes are excellent and effective adsorbent for eliminating these harmful media in water. The effects of the morphologies and the surface status on the carbon nanotube adsorption capacities are also discussed.

Cu-catalyzed ZnO nanowires have been synthesized by thermal evaporation of Cu- Zn powder alloys in a water vapor atmosphere. The diameters of the nanowires can be controlled by the amount of water vapor introduced into in the reaction tube. Raman spectroscopic characterization reveals two additional modes at 621 and 671cm⁻¹ which are indicative of the existence of host-lattice defects caused by Cu doping or other intrinsic lattice defects that formed during the nanowire growth. Field emission and photoluminescence (PL) properties of Cu-catalyzed ZnO nanowires have also been investigated using nanowires with a diameter of 20 nm and 200 nm. The field emission results show that the thinner nanowires have a lower turn-on electrical field than the thicker ones, whilst both nanowires exhibit a similar field emission enhancement factor in the high electric field region. In the PL spectra, we have observed a blue-shift of the UV emission peak and a red-shift of the green emission peak when the nanowire diameters decreased from 200 nm to 20 nm.

Concentrations of the Si-H vibration bond and the dangling bond in amorphous silicon films were studied using FTIR and ESR techniques respectively as a function of annealing temperature in the range from 20°C to 950°C. It was found that the concentration of Si-H did not change much for temperatures up to 350°C and then dropped monotonically and became negligible at temperatures above 850°C, while the concentration of SiH₂ increased with temperature and attained a maximum at 450°C and then decreased with temperature there after. The ESR signal dropped with temperature, up to 200°C, and fell below the detection limit of our spectrometer in the range 200°C-500°C. The ESR signal recovered when annealing temperature was higher than 550°C. The Si-H, SiH₂, ESR and optical absorption signals were found to be highly correlated to each other and could be interpreted in a consistent manner.

In an infinitely large diffusive n-type 2D semiconductor with Rashba spin-orbit coupling, the spin-Hall conductivity σSH vanishes due to the cancellation of its intrinsic and impurity-related contributions, independently of temperature, of the spin-orbit coupling constant, of the impurity density, and of the specifc form of the electron-impurity scattering potential. In this paper, we demonstrate that such a precise cancellation is associated with the continuity of electron momentum in infinitely large sample and hence may be removed when the size of the sample is reduced. Considering a square sample with side length, L, we find that depending on L in the micrometer range, σSH can be positive, zero or negative with a maximum absolute value reaching as large as e/8π order of magnitude at low temperatures. As L increases, σSH oscillates with a decreasing amplitude. Such a size effect shows up only at low temperatures. When temperature increases the σSH oscillations disappear and spin-Hall conductivity takes a small finite value before slowly approaching zero with further increasing the sample size to L < = 20 micrometer. The present study indicates that a nonvanishing spin-Hall conductivity may be obtained in a 2D Rashba electron systems of micrometer size, notwithstanding its disappearance in infinitely large samples. For it to appear, one has to accurately control the shape and size of the sample. In addition, the mobility of the sample should be high and the temperature should be low that both the collisional broadening of the electron energy level and the temperature smearing are smaller than the finite-size induced energy separation of the electron states around the Fermi surface.

The dielectrophoretic concentration of DNA particles suspended in a solution is investigated in a system of parallel electrodes, where the particles are attracted to the edges of the electrodes by positive dielectrophoresis. The AC electroosmotic motion of the fluid is also considered, as well as the diffusion of the particles, using the solution of the Smoluchowski equation. The results examine the effect of AC electroosmosis in steady state dielectrophoretic concentration of particles, by demonstrating that AC electroosmosis significantly reduces the dielectrophoretic concentration at the edges and moves the particles towards the electrode centres.

Specifisities of deformation on nanoscale of hard brittle materials with the hardness exceeding 10 GP by means of scanning probe microscope - nanohardness tester "NanoScan" are investigated. It is found, that pile-up is forming at scratching of sample surface with use of diamond indenter. Heigh of this pile-up depends on hardness and elastic modulus of the material. Definition of the contact area without taking into account height of pile-up leads to an overestimation of hardness values. At scratching of silicon carbide surface a transition from plastic flow to fracture is found out. The results received allowed to estimate fracture toughness K_IC for silicon carbide.

The use of doped full-diamond tips in SPM to measure electrical properties with nanoscale resolution is described. The method enables to measure electrical impedance, capacity and conductivity of semiconductors. The experimental results shows a wide range of benefits in investigation and creation of elements for micro and nano-electronics. According to multiple experiments, the characteristics of diamond tips are very stable during scanning, indenting and electrical measurements.

Plasma-modified PET-monofilaments, newly developed functional bicomponent fibers and electrospun PEO-nanoscaled fibers were investigated using the atomic force microscope. Contact mode measurements revealed small changes in topography by changing the oxygen-content during hexamethyldisiloxane plasma-deposition. Adhesion measurements proved the increasing surface energy with increasing oxygen-content as calculated by JKR theory. Simultaneous measurements of the topography and phase shifts on bicomponent fibers demonstrated the change of the surface roughness and elastic homogenity of the PET-surface after hydrolysis with NaOH solution. Cross-sectional imaging showed differences in thermal expansion and hardness of bicomponent fibers. Nanoscaled unsupported electrospun fibers were visualized in the dynamic mode. Bending of differently drawn bicomponent fibers by the AFM-cantilever allowed direct access to the elastic modulus.

A combined Scanning Probe Microscope (SPM) - nanoindentation instrument enables submicron resolution indentation tests and in-situ scanning of structure surfaces. A newly developed technique is based on the scanning tunneling microscopy (STM) with integrated Berkovich diamond semiconductive tip. Diamond tips for a combined SPM were obtained using the developed procedure including the synthesis of the semiconductive borondoped diamond monocrystals by the temperature gradient method at high pressure - high temperature conditions and fabrication of the tips from these crystals considering their zonal structure. Separately grown semiconductive diamond single crystals were studied in order to find the best orientation of diamond crystals. Optimal scanning characteristics and experimental data errors were calculated by an analysis of the general functional dependence of the tunneling current from properties of the tip and specimen. Tests on the indentation and scanning of the gold film deposited on the silicon substrate employing the fabricated tips demonstrated their usability, acceptable resolution and sensitivity.

We investigate the dynamics of electrons injected into InAs/GaAs quantum dots by initializing and further observing the spin state of the electrons. For this purpose, we use spin polarized light-emitting diodes where the electron spin is set in a semimagnetic ZnMnSe layer. We find that the degree of optical polarization depends strongly on the ground state energy of the quantum dot. A dependence of polarization on dopant concentration in the spin aligner suggests an influence of residual electrons in the quantum dots.

Polycrystalline silicon were grown at high temperature in a gas-source molecular beam epitaxy (MBE) and then exposed to cavitation impacts from the backside at different scanning times to introduce compressive stress. The micro-Raman spectroscopy showed that regions of greater structural change due to cavitation impacts experience higher full width at half maximum (FWHM) and that stress was a function of number of scans. AFM was used to analyze the surface morphology of the specimen in the as-grown condition and after exposed to cavitation impacts. The structural features were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). HRTEM observations showed that nanoparticles size of grains at the growth/death zone of interface. The dislocations types, twinnings and defects caused by cavitation impacts are discussed.

Visible-light photocatalytic activity of metal-doped TiO₂ films prepared by dipcoating method was investigated. Cu, Fe, and Al atoms were doped in the TiO₂ films and they exist as their oxide in the nearly stoichiometric TiO₂ matrices. It is found that the Cu doping is effective for visible-light photocatalysis of the TiO₂ films, while Fe- and Al-doped films hardly shows visible-light photocatalytic activity. The optical absorption spectra for the non-doped and metal-doped TiO₂ films show that effective band gap narrowing is observed in the Fe- and Cu-doped TiO₂ films. Recombination of the photogenerated electron/hole pairs takes place quickly in the Fe-doped TiO₂ film, while the charge separation of the photogenerated electron/hole pairs takes place effectively in the Cu-doped TiO₂ film. Al doping into the TiO₂ film has hardly effect on photocatalysis of TiO₂ films.

The electronic structure of the MAX-phase Ti₂AlC was investigated by soft x-ray emission spectroscopy. This nanolaminated carbide compound represents a class of layered materials with a combination of properties from both metals and ceramics. The bulk-sensitive soft x-ray emission technique is shown to be particularly useful for detecting detailed electronic structure information about internal monolayers and interfaces. The Ti-Al bonding is manifested by a pronounced peak in the Ti L-emission of Ti₂AlC, which is not present in the binary TiC system. The spectral shape of Al L-emission in the MAX-phase is strongly modified in comparison to metallic Al. By replacing the constituting elements, a change of the electron population can be achieved causing a change of covalent bonding between the laminated layers, which enables control of the macroscopic properties of the material.

The analysis of experimental amplitude and phase curves and phase images of polymer blends was performed in combination with KBM (Krylov-Bogoliubov- Mitropolsky) modelling of tapping mode atomic force microscopy (AFM). Different phase and dissipation contrast of images of multilayer polymer blends suggests that phase imaging is better for compositional mapping whereas understanding of the dissipative processes will facilitate a quantitative description of tip-sample force interactions in this mode. The KBM model describes tapping mode amplitude and phase curves in terms of three stationary solutions (two stable nodes, one saddle) verified by the experiment. A simple model of energy dissipation (adhesion avalanche) was also considered.

Novel diamond/sapphire probes are introduced for different scanning probe microscopy applications: from nanoindentation to high-resolution imaging of soft samples. These probes have sharp diamond tips with apex size below 10 nm and their stiffness/resonant frequency and tip shape can be adjusted for customer needs. Several examples of imaging with novel probes are given. Probes with conducting diamond tips exhibited high-sensitivity in electric force microscopy study.

We present a study of the growth of silver clusters on a TiO₂(110) substrate in ultrahigh vacuum. The growth is monitored in situ by Low Energy Ion Scattering (LEIS) using He+ scattering and X-ray Photoelectron Spectroscopy (XPS) and ex situ by scanning electron microscopy (SEM). Experimental results show that the deposition rate, the substrate temperature and the annealing temperature are key parameters for controlling the size and morphology of the Ag clusters. By changing the deposition rate, the mean cluster diameter can vary from 5 to 20 nm. The growth of Ag at low substrate temperature shows a transition from quasi 2D flat islands to a 3D growth mode at submonolayer coverage. The substrate was annealed at different temperatures and the clusters shape controlled from a quasi 2D flat island to 3D sharp islands with a maximum substrate exposure, prior to cluster desorption.

Using the Digital Pulsed Force Mode (DPFM) approach, the local mechanical properties of living HeLa cells have been examined. The cells were attached to a favorable glass-like substrate. The AFM used for the experiments was a commercial AFM setup by WITec. At every point of the image, approach and retract curves have been performed. The repetition rate of the cycle was 175 Hz. A total of about 500,000 curves has been recorded and completely evaluated for each experiment. The substrate served as an online reference material for calibration purposes. First, the force trajectories were corrected for the viscous drag force in the liquid environment. Second, the curves within the region of the substrate were phase corrected to compensate for the time lag of the signal in the setup assuming a purely elastic response of the reference material. Finally, all the force traces have been corrected by using this information and evaluated according to common continuum-elastic models. The resulting images allow the assignment of values of Young's modulus, local adhesion, hysteretic behavior, etc. at a high lateral resolution all over the cell body. In this paper, we describe the procedure of our measurement and the corresponding signal correction strategy of our automated data evaluation.

Toward the development of a simulator of scanning probe microscope for systems with adsorbed organic molecules, we simulate non-contact atomic force microscope images of hydrogen-terminated Si(001)2×1 surfaces with an isolated methyl using a Si tip with and without a hydrogen atom at the apex, using a density-functional based tight-binding method. We examine the constant height, constant frequency and energy dissipation images. In addition to normal images of constant height and constant frequency modes, we obtain the exotic energy dissipation images, where a low dissipation spot is surrounded by a ring of high dissipation region. These images can be understood from the site-dependence of force hysteresis.

Thin Si films prepared by plasma enhanced chemical vapor deposition at low temperature and containing microcrystalline grains in amorphous tissue were studied by two complementary microscopy techniques. The conductive atomic force microscopy was performed in standard ambient conditions, whereas the presence of the surface oxide was overcome by more sensitive (pA) current detection. The cross-sectional transmission electron microscopy images of the amorphous phase revealed the columnar structure, which was successfully correlated with the bumpy surface detected by the atomic force microscope.

Here we present an Ultra High Vacuum Scanning Tunnelling Microscopy (UHVSTM) and Scanning Tunnelling Spectroscopy (STS) study of self assembled donor-acceptor conjugate dyads, consisting of fulleropyrrolidines and metallo-porphyrins immobilized on gold. The coverage in the fulleropyrrolidine layers was optimized up to obtain isolated protrusions which we identify with isolated dyads since their lateral dimensions are consistent with the fullerene size. The STS study reveals a diode-like asymmetric behaviour of the dyads, different from the surrounding areas. We investigate also the influence of the tunneling conditions on the rectifying ratio which is found to be dependent on the initial set point conditions and to increase by increasing the tip-sample distance.

Results of a study designed to investigate the possibility of using the Si(111)- Ge(5×5) surface reconstruction as a template for In cluster growth are described. As with Si(111)-7×7, the In adatoms preferentially adsorb in the faulted half-unit cell, but on Si(111)- Ge(5×5) a richer variety of cluster geometries are found. In addition to the clusters that occupy the faulted half-unit cell, clusters that span two and four half-unit cells are found. The latter have a triangular shape spanning one unfaulted and three, nearest neighbor, faulted half-unit cells, Triangular clusters in the opposite orientation were not found. Many of the faulted halfunit cells have a streaked appearance consistent with adatom mobility.

We have implemented a technique to eliminate the in-plane lateral tip motion for AFM experiments that involve a cantilever deflection change due to bending. Because of the geometry limitation, there is an undesired lateral tip position change associated with the bending of the cantilever. Previous approaches for solving this problem used X-piezo motion to compensate this tip lateral motion based on the distance change between the tip and sample, or the Z-piezo travel. This method partially works based on the assumption that the cantilever deflection change is always proportional to the Z-travel distance, which is not true in many cases. The key factor in our approach is to apply X-piezo motion based on the cantilever deflection change. This is a direct and accurate method that will also take into account of the probe sample interactions. We will demonstrate the application results of this method with nanoindentation on polymer samples, as well as imaging on heterogeneous materials. The various kinds of calibration methods will be also discussed.

Research supported by NIST/ATP Award #70NANB4H3055.

Three-dimensional morphological and compositional structures of tungsten tips consisting of layered amorphous oxide shell and crystalline W core are reconstructed by electron tomography using both coherent and incoherent imaging modes. The fidelity of the reconstruction is dependent on three criteria, suppression of unwanted crystal orientation contrast in the crystalline core, nonlinear intensity-thickness relations above a certain thickness limit, and artefacts due to missing angular ranges when acquiring a tilt series of images. Annular dark field (ADF), and EDX chemical mapping are discussed as alternatives to standard bright field (BF) TEM imaging.

Vertically aligned Fe-filled multi-wall carbon nanotubes (MWNTs) have been grown selectively on the SiO₂ surfaces of patterned amorphous carbon (a-C)/SiO₂/Si substrates. Their morphology, structure and magnetic properties have been studied. The a-C patterns were prepared using conventional lithography processes combined with a sputter-deposition of a-C (thickness of 100 nm). The aligned Fe-filled MWNTs were produced by pyrolysis of ferrocene in a CVD reactor with a two zone furnace system and have high filling yield. The encapsulated Fe nanowires grown on the SiO₂ structures of the patterned a-C/SiO₂/Si substrates have diameters of 10-20 nm and can reach a few micrometers in length. The described method enables the preparation of complex architectures of Fe-filled MWNTs and may be used for future applications based on filled nanotubes.

Multifunctional nanocontainers can be produced based on partially filled Fe-multi walled carbon nanotubes (MWCNTs). Using thermal decomposition ferrocene filled nanotubes can be grown aligned on substrates. The encapsulated metal nanowires have diameters of 5-30 nm and a length up to few microns. They consist of single-crystalline of α and γ-Fe- phases. Using heat treatment, it is possible to transform γ-Fe into α-Fe. With the aid of wet chemical methods the nanotubes can be opened and additionally filled with an agent, e.g., therapeutic agents (carboplatin) or other metals (copper). Initial studies do not show a high toxicity over a period of 440 days. These materials can be used for drug delivery and hyperthermia. The specific absorption rate (SAR) is greater than 100W/(g-α-Fe) in a magnetic field of 18kA/m (f = 250kHz).

Anionic clays or layered double hydroxides (LDHs) are one of the nano ordered layered materials. The layered double hydroxide well known for its ability to intercalate anionic compounds is prepared conventionally only with divalent and trivalent cations, hi this study, Co-Sn LDH consisting of divalent and tetravalent cations was prepared and reacted with monocarboxylic acids at room temperature. The Co-Sn LDH and intercalated compounds were characterized by chemical analysis (C, H, N analysis, ICP and ESCA), energy dispersive X-ray spectrometer (EDS), X-ray powder diffraction (XRD), infrared spectra (IR), thermal analyses (TG, DTG and DTA) and scanning electron microscope (SEM). The insertion of cyanate and carbonate anions into LDH was confirmed by chemical analysis and IR spectra. XRD patterns of the prepared Co-Sn LDH showed that the interlayer spacing of the LDH was 0.78 nm. The spacing was similar to that of usual LDH in which chloride, carbonate or bromide anion is the guest. SEM images showed that the aging time plays a vital role in the formation of Co-Sn LDH. The morphology of Co-Sn LDH was plate-like structure and/or fibrous structure depending on the aging time and the kind of interlayer anion.

Optical and atomic force microscopy measurements on the {001} form of the organic semiconductor quaterthiophene revealed interlaced spiral patterns arising from growth layers mutually rotated by 180° about the normal to the (001) crystal face. This bulk-surface relationship, along with the height of the exposed step ledges of the order of 10-100 nm, evidences the complex polytypic nature of these crystals in which the basic P2₁/c layer gives rise to several different stacking along [001], even within the same crystallite. The consequences on solid state physical properties arising from these crystal growth phenomena are briefly discussed.

Concentrated-mass (CM) cantilevers previously proposed by the author have features significantly effective for atomic force acoustic microscopy (AFAM), in which sample stiffness can be detected at nano scale by a vibrating tip. CM cantilevers improve the sensitivity of the detection and simplify the dynamics then lead to success in evaluations of the elastic modulus. The present study proposed a new type of CM cantilevers based on analyses of the vibrational dynamics taking account of previously ignored factors including the lateral contact stiffness and the inertia moment of a particle attached as a CM. A rod-like particle was attached on a tip in the new type to enhance the inertia moment in addition to the translational inertia. The first two modes behaved like one-freedom models, namely translational (vertical) and rotational (lateral) motions of the attached mass and the tip. Experiments on a sapphire wafer verified that the vertical and lateral stiffness can be simultaneously evaluated without mutual interference.

Carbon-based solids with active surface sites, including electrically conductive diamond-like carbon (DLC), will undergo electro-oxidative conversion to CO₂ in an aqueous phase; the reaction takes place either in a thin film of adsorbed moisture, or in an aqueous fluid cell. The process can be localized by conventional masking, or by a mask-less configuration based on using a scanning tunneling probe as a proximity electrode. In the former case the technology is parallel and spatial resolution is determined by the masking, while in the latter case the technology is serial, but line widths of 10 nm can be obtained.

Electro-oxidation of carbon-based materials will lead to conversion of the solid to CO₂/CO at the anode, with H₂ being produced at the cathode. Recent voltammetric investigations of carbon nano-tubes and single crystal graphite have shown that only edge sites and other defect sites are electrochemically active. Local oxidation of diamond-like carbon films (DLC) by an STM tip in moist air followed by imaging allows correlation of topographical change with electro-chemical conditions and surface reactivity. The results may have implications for lithographic processing of carbon surfaces, and may have relevance for electrochemical H₂ production.

Mixed monolayers of mercaptoundecylferrocene and undecanethiol were deposited from solution by coadsorption and by a two-step insertion method, using the alkanethiol monolayer as insulating matrix. The resulting layers were characterized by UHV-STM, showing molecular resolution. For insertion-processed samples, a mesh-like surface structure of ferrocenes was observed, due to the preferential incorporation of molecules along domain boundaries and defect sites of the alkanethiol monolayer. For monolayers in the intermediate coverage regime, a crystalline phase was observed.

We developed a new nanotool of scanning probe microscopy (SPM) for local conductance measurement. Two Pt electrodes with a nanogap fabricated by focused ion beam (FIB) milling are integrated on a Si cantilever with Al electrodes. The minimum gap fabricated on the cantilever is 20 nm. Local conductance measurements of conductive materials, a carbon film and a gold film, were performed using the nanogap probe on a conventional SPM system. Ohmic contacts between the gap electrodes and the conductive samples were established. The resolution of the conductance image is almost the same as the gap distance of the electrodes. A single gold grain was successfully imaged with sub-100-nm resolution.

The effects of the material parameters and processing conditions on the foam morphologies, and mechanical properties of polymer/clay nanocomposite foams were studied. Microcellular closed-cell nanocomposite foams were manufactured with poly(methylmethacrylate) (PMMA) and high density polyethylene (HDPE), where the nanoclay loadings of 0.5, 1.0, and 2.0 wt% were used. The effect of clay contents and foaming conditions on the volume expansion ratio, cell size, elastic modulus, tensile strength, and elongation at break were investigated and compared between amorphous and semicrystalline polymers. An elastic modulus model for tensile behavior of foams was proposed by using the micromechanics theory. The model was expressed in terms of microstructural properties of polymer and physical properties of the foams. The tensile experimental data of the foams were compared with those predicted by the theoretical model.

We show that physisorbed octadecylphosphonic acid (OPA) self-assembled monolayer (SAM) molecules on a Si substrate can be removed by a biased conductive probe tip. Our experimental results suggest that the OPA headgroups are negatively charged and adsorbed on the Si substrate through weak electric charge interaction, allowing one to selectively remove these molecules from their SAMs with an electric field.

The local density of states (LDOS) at the epitaxially grown InAs surface on a GaAs substrate was studied at very low temperatures in magnetic fields up to 6 T by scanning tunneling microscopy and spectroscopy. We observed a series of peaks, associated with Landau quantization of the two-dimensional electron system (2DES), in the tunnel spectra just above the subband energy (-80 meV) of the 2DES. The intervals between the peaks are consistent with the estimation from the effective mass of the 2DES at the InAs surface. In a wider energy range, another type of oscillation which was independent of magnetic field was also observed. This oscillation can be explained by the energy dependence of the transmission probability of the tunneling current through the Schottky barrier formed at the interface between the InAs film and GaAs substrate.

We have studied the effect of the plasmon field on the STM-induced luminescence from porphyrin (H₂TBPP) film on Au substrate. We have measured the spectrally resolved photon intensity map for the STM-induced luminescence, and found the similarity of their contrast for the photon maps for different spectral regions with different spectral origins, i.e. molecular fluorescence and the local plasmon induced luminescence from the substrate. This fact indicates that the molecular fluorescence is closely related with the plasmon field of the substrate, and supports that the STM-induced fluorescence from porphyrin film on Au is enhanced by the local plasmon field of the Au substrate.

We grew In nanowires on In-rich InGaN layers with In content of 80% using focused ion beam system equipped with Ga liquid metal source. The experiments were performed at room temperature without any cooling or heating source, and the whole growth process can be monitored in-situby field emission scanning electron microscope / FIB dual beam system. The nanowires were observed only at the ion beam irradiation area, and the length and diameter of nanowires were controlled by adjusting accelerating voltage. The energy dispersive x-ray spectroscopy and the electron diffraction pattern of nanowires using transmission electron microscope confirmed that the composition of nanowire was indium, and the In nanowire was grown along the [-1 1 2] direction. This In nanowire induced by FIB irradiation grew with the ultra-fast growth rate as fast as 8 μ/min. The growth of In nanowires was supposed to be caused by ion irradiation-induced phase decomposition.

Builiding on earlier studies of single InGaN quantum dots (QDs), we are considering their potential for use in blue- and green-emitting single photon sources. Envisaging a device based on a resonant cavity light emitting diode, we have studied the effect of growing QDs on an underlying AlN/GaN distributed Bragg reflector, and have shown that enhanced single QD emission may be obtained. Additionally, we have studied the effect of the growth and activation of a p-type cap on an underlying QD layer and have shown that the QDs survive the anneal process.

We have investigated random submonolayer films of 3d transition metals on W(001). The tight-binding linear muffin-tin orbital method combined with the coherent potential approximation was employed to calculate the electronic structure of the films. We have estimated local magnetic moments and the stability of different magnetic structures, namely the ferromagnetic order, the disordered local moments and the non-magnetic state, by comparing the total energies of the corresponding systems. It has been found that the magnetic moments of V and Cr decrease and eventually disappear with decreasing coverage. On the other hand, Fe retains approximately the same magnetic moment throughout the whole concentration range from a single impurity to the monolayer coverage. Mn is an intermediate case between Cr and Fe since it is non-magnetic at very low coverages and (ferro)magnetic otherwise.

When a C₆₀ film is irradiated with a 3-kV electron-beam (EB), a peanut-shaped C₆₀ polymer with metallic properties is formed. Valence photoelectron spectra of the polymer indicated that the density-of-states (DOS) of the polymer clearly comes across the Fermi edge in a manner similar to that of Au film used as a reference. Interestingly, the spectral function of the peanut-shaped polymer around the Fermi edge resembles that of quasi one-dimensional (1D) materials such as K_0.3MO₃ with its metallic phase. This suggests that the peanut-shaped polymer has also a quasi 1D structure and may exhibit the Peierls transition at a given temperature. If the polymer shows the metal-insulator transition at the given temperature, the transition would change the electron-transport mechanism of the polymer. Then, we examined the temperature-dependence of the electrical conductivity of the polymer in the range of 9K-400K. It is found that the electron transport mechanism was changed at approximately 90 K, suggesting that the valence electronic structure around the Fermi edge was changed at this temperature.

The adsorption of different alkanes (linear and cyclic), aromatics and chlorohydrocarbons on non-microporous carbons-carbon nanotubes (CNTs) and carbon nanofibres (CNFs)- was studied in this work by inverse gas chromatography (IGC). Capacity of adsorption was derived from the isotherms of adsorption, whereas thermodynamic properties (enthalpy of adsorption, surface free energy characteristics) have been determined from chromatographic retention data. CNTs present the highest adsorption capacity. From surface free energy data, enthalpies of adsorption of polar compounds were divided into dispersive and specific contributions. The interactions of cyclic (benzene and cyclohexane) and chlorinated compounds (trichloroethylene, tetrachloroethylene and chloroform) with the surfaces are mainly dispersive over all the carbons tested, being CNTs the material with the highest dispersive contribution. Adsorption parameters were correlated with morphological and chemical properties of the materials.

We consider a quasi one-dimensional configuration consisting of two small pieces of ferromagnetic material separated by a metallic one and contacted by two metallic leads. A spinpolarized current is injected from one lead. Our goal is to investigate the correlation induced between the magnetizations of the two ferromagnets by spin-transfer torque. This torque results from the interaction between the magnetizations and the spin polarization of the current. We discuss the dynamics of a single ferromagnet, the extension to the case of two ferromagnets, and give some estimates for the parameters based on experiments.

The soft deposition of Cu and Au clusters on Au(001) and Cu(001) surfaces respectively is studied by constant-temperature molecular-dynamics simulations. The initial shape of the nanoclusters is icosahedral or truncated octahedral (Wulff type). Their number of atoms ranges between 12 and 1289 atoms. Bombardment energy is of the order of a few meV/atom. The atomic interactions are mimicked by a many-body potential based on the tightbinding model. The effect of the temperature as activation to get the complete epitaxy is analysed. We have found that Cu clusters manage to align their {002} planes with the substrate by increasing the temperature. However, there is not epitaxial growth in any case since the lattice becomes bcc or important stacking faults are generated. For Au clusters, the alignment of these planes is practically independent of the temperature.

Morphological modifications of the cellular membrane of human keratinocytes treated with HgCl₂ at different concentrations were investigated employing atomic force microscopy and Raman microspectroscopy techniques. Important changes in the surface structure of the keratinocytes membrane occur when this chemical treatment is performed. Mercury action gives rise to roughness and hole-like depressions, especially at cytotoxic concentration. Such surface features are mainly localized in peripheral zones of cells. Although the viability assay reveals that the exposure of keratinocytes to HgCl₂ at a concentration of 10⁻⁶ M has no cytotoxic effect, morphological modifications are also evident in cellular membrane at such concentration. Raman microspectroscopy measurements suggest that such morphological modifications are related to modifications occurring in the lipidic layer. Our findings show that atomic force microscopy can be a valid and useful tool in studying the changes in morphology of cells when exposed to chemical stress.

Low-temperature scanning tunneling spectroscopy under ultra-high vacuum was employed to investigate the two-dimensional electron system at the epitaxial surface of Sidoped In_0.53Ga_0.47As/In_0.52Al_0.48As(111)A quantum-well structures. The electron density in the near-surface region of the quantum well could be controlled through modulation doping. Spectra of the electronic local density of states in the conduction band showed a clear step-like energy dependence that reveals the subband states. In spectra acquired at some areas of nanometer size, peaks were observed near subband minima, indicating the existence of bound states.

This work shows that a set of quality indicators (QI), able to reliably monitor the basic characteristics of carbon nanotubes (CNT) grown by of Fe-catalysed chemical vapour deposition (CVD), can be derived from Raman spectroscopy (RS) measurements. Multi-walled nanotubes, prepared at 750 °C in C₂H₆+H₂ mixture over 20%Fe/SiO₂ catalyst, are demonstratively considered. By quantitatively analysing the spectra measured in the 100-3100 cm⁻¹ range, information is obtained on level of defectiveness and degree of smoothness of C deposits, as well as, on relative amount of Fe-nanoparticles incorporated. The effect of the growth atmosphere composition on the quality of synthesis products is investigated. Indications provided by RS are confirmed by the results of scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses. Raman QI agreeably correlate with the average growth rate of the carbonaceous species.

The conduction band electron states of laterally-coupled semiconductor quantum rings are studied within the frame of the effective mass envelope function theory. We consider the effect of axial and in-plane magnetic fields for several inter-ring distances, and find strong changes in the energy spectrum depending on the coupling regime. Our results indicate that the magnetic response accurately monitors the quantum ring molecule dissociation process. Moreover, the anisotropic response of the electron states to in-plane magnetic fields provides information on the orientation of the quantum ring molecule.

The scope of this paper is to analyse the effect of Au and Cr impurities, diffused onto GaSb substrates on the formation of nanodots created by LEIS using Ar+ ions It is concluded that oblique incidence in rotating configuration delays the formation of the nanodots compared to previously reported normal incidence experiments. The presence of cracks induced by the sputtering process has been observed both in the Au and Cr diffused samples. Cathodoluminescence (CL) spectra obtained in irradiated samples both pure and Crdiffused have revealed no difference between them, showing the usual three band encountered in this material (Band Gap at 798 meV, A Band at 777 meV and tail-states at 815 meV). However, a fourth band has been detected in the Au sample centered at 769 meV.

Analytical expressions giving the noise power spectral densities of the signals of interest in frequency modulation-dynamic force microscopy are derived. They are validated by comparison with numerical simulations performed with a realistic virtual force microscope. Thermal noise as well as detection noise are considered. A tip-substrate interaction incorporating a van der Waals and a Morse potential is considered as an illustrative example.

Atomic Force Microscopy (AFM) techniques are used with one- or two-dimensional arrays of piezoresistive probes for parallel imaging. We present a newly designed AFM platform to drive these passivated piezoresistive cantilever arrays in air and liquid environments. Large area imaging in liquid as well as qualitative and quantitative analysis of biological cells are demonstrated by the means of piezoresistive cantilever for the first time to our knowledge. Noise limitations in topography and force resolutions of these piezolevers are quantified.

Nanostructured AgCl layer acts as photocatalyst for water oxidation in the presence of a small excess of Ag⁺ in solution. The photoactivity of AgCl extends from the UV into the visible light region due to self-sensitization, caused by the formation of silver species during the photoreaction. Anodic polarization reoxidizes the produced silver species. Experiments were carried out with spherical gold as well as spherical and prismatic silver nanoparticle modified AgCl layers. We observed that traces of these nanoparticles greatly influenced the photoelectrochemical activity. With spherical gold nanoparticle modification, the O₂ production and the photocurrent increased by a factor of about 3, as compared to layers without gold colloids. Also spherical and prismatic silver nanoparticles led to an increased O₂ production and photocurrent.

Thin films of ligand-stabilized Au₅₅ clusters deposited on Au(111) and highly oriented pyrolytic graphite (HOPG) substrates have been investigated by noncontact atomic force microscopy (NC-AFM) and spectroscopy. The NC-AFM images show small size islands (consisting of one up to 20 clusters) on the Au(111) substrate which are locally ordered. In contrast, on HOPG, the clusters stick together in disordered monolayer islands of larger size. Conservative and dissipative interactions between the AFM probe and individual Au₅₅ clusters have been investigated for the two systems. The force as well as the dissipation curves show different behavior for the two systems.

Nanoparticles are becoming increasingly important in many areas, including catalysis, biomedical applications, and information storage. Their unique size-dependent properties make these materials superior. Using the Atomic Force Microscope (AFM), individual particles and groups of particles can be resolved and unlike other microscopy techniques, the AFM offers visualization and analysis in three dimensions. We prepared titanium oxide, zirconium oxide and alumina nanoparticles and/or agglomerates on different surfaces and characterized them by AFM in the dynamic mode. The goal was to determine the shape, size and/or size distribution of nanoparticles. Different dilutions of nanoparticles were applied on various substrates e.g. clean silicon, mica and chemically treated silicon and imaged at ambient conditions. Nanoparticles deposited on mica appeared to be coagulated as compared to those on silicon. Whereas, on a chemically treated surface the density of the nanoparticles was very low because of the increased hydrophobicity of the surface.

Our empirical method to fabricate molecular dots from thin organic films by dewetting, is further developed and quantified. The films are deposited at UHV conditions on helium-cooled substrates. Controlled annealing to room temperature transforms the films into homogeneous distributions of isolated dots. To achieve regular and closely packed patterns of nano-dots we applied the dewetting process on topographically structured substrates as templates. The dots are characterized and accessed by scanning microscopies.

Mercury-plated as well as bare nitrogenated diamond-like carbon (NDLC) microelectrode arrays have been investigated for application in in-situ determination of heavy metals (Cu, Pb and Cd) by differential pulse anodic stripping voltammetry (DPASV). A microelectrode array consisting of 50 625 microdiscs with 3 μm in diameter and interelectrode distances of 20 μm was fabricated on a highly conductive silicon substrate and characterized by CV measurements. Current responses of all metals were linear for metal concentrations in the range of 1.6 × 10⁻⁸ to 8.3 × 10⁻⁸ mol/L and preconcentration time 5 min. The stripping current responses of the bare microelectrode array reached under the same conditions were much lower in comparison with a mercury-plated array. A strong effect upon stripping current responses of metals was observed of adding a small amount of thiocyanate (2 × 10⁻³ mol/L) into the plating solution.

The mechanically controllable break-junction technique enables us to investigate charge-carrier transport through an individually contacted and addressed molecule. Using a statistical measurement and analysis approach, we acquire simultaneously current-voltage curves during the repeated formation and breaking of a molecular junction. Thereby, a reversible and controllable switching between two distinct conductive states of a single-molecule system was investigated. Voltage pulses are used to switch from a low to a high conductive ''on'' state, and, furthermore, to reset the switch again to the ''off'' state. On this single-molecule level, collective phenomena can be excluded and therefore the observed switching mechanism has a truly molecular origin. Both conductive states are stable and accessible via non-destructive reading. Combined with the ability to reset the switch, this opens the way to employ this single-molecule as a memory element which is demonstrated by repeated write-read-erase-read cycles with non-destructive read-outs.

GaAs nanowires were synthesized by molecular beam epitaxy on different substrates using Mn as catalyst. High density of 1D nanowires was obtained at growth temperature between 540 and 620 °C on SiO₂ substrates. On oxidised GaAs substrates nanowires grow together with 2D nanostructures that are dominant. Nearly no nanowires were instead obtained on epitaxial GaAs. The nanowire yield on the different substrates is correlated to the chemical reactions taking place between substrate and catalyst before the growth, as detected by x-ray photoelectron spectroscopy.

Changes in some electrical and photoelectric parameters in the plane of aluminum gate, particularly in the effective contact potential difference (ECPD or ϕ_MS factor) have been observed in MOS System Studies Department of Institute of Electron Technology for the first time. It has been found that the MS distribution over the gate area has a characteristic domelike shape, with the highest values ate the center of the gate, lower at the gate edges and still lower at gate corners. In order to find out why these values were changed in such way, we have investigated optical properties of the dielectric in the neighborhood of metal gate. Hence, in this work, interferometry and spectroscopic ellipsometry as well as scattered Raman radiation analysis have been used in the investigation of metal-oxide-semiconductor (MOS) structures. The above mentioned methods turned out to be very useful for the possible explanation of changes in photoelectric characteristics of MOS structures with aluminum gate.

Nanostructured materials based on Zr-Al-Ni-Cu metallic glasses have been synthesized by controlling the nucleation and growth rates of the precipitated phase correlated with the unique icosahedral local structure. It is well known that the Zr₆₅Al_7.5Ni₁₀Cu_17.5 metallic glass has a high glass-forming ability (GFA), which enables us to produce the glassy sample with a bulky shape. By substitution of Pd with Cu, the primary phase changes from the metastable fcc-Zr₂Ni phase into the nanoscale icosahedral quasicrystalline phase (I-phase). It is found that the nucleation frequency increases drastically with the Pd addition, which results in the formation of nanostructured materials. The nanoscale structure control in metallic glasses exhibits unique mechanical properties such as a high strength and good ductility.

We performed the measurement of the dynamic viscoelasticity of a single polymer chain by the self-produced piezo-control and data acquisition system externally built on the commercial atomic force microscope (AFM). The sinusoidal movement with the small amplitude was applied to a single polymer chain at the several points in the middle of elongation, and the response of the molecule was evaluated. As the result of the experiment, some dissipative behavior was observed in the low-elongation region of the polymer chain, which could have never been observed in the simple elongation experiment. This behavior may be due to the friction between the monomers constituting a polymer chain.

We numerically investigate electron transfers in nanowires which consist of deoxyribonucleic acid (DNA) molecules (up to five base pairs for double-strands and seven bases for single-strands) by quantum dynamical calculations. DNA molecules are applied to organic nanodevices and the performance depends on electronic transfer properties. Combining quantum chemical molecular-orbital calculations and stochastic mechanics, we provide an analyzing method of quantum dynamical electron motions. From one-electron wavefunctions or molecular orbitals, we calculate some dynamical properties, such as mean-square displacement and self-diffusion coefficients relating with electron mobility. Our calculation suggests that the electron transfers through the double-strands of GC base pairs while the electrons are localized in the double-strands of AT base pairs nor the single-strands of G bases.

This report presents the use of disulfide-modified single-stranded DNA (ssDNA) to form DNA self-assembled monolayers (SAMs) and mixed DNA-carbon nanotube (CNT) hybrids SAMs on gold substrates. Mixed DNA-CNT SAMs are composed of DNA, mercaptohexanol (MCH) and DNA-CNT aggregates. Both, DNA-CNT and DNA areas of the mixed SAMs were analyzed and compared to traditional DNA SAMs. The results suggest the formation of a more compact and densely packed monolayer of DNA-CNT in comparison with DNA. The use of DNA-CNT hybrids to form SAMs on gold substrates might represent a new approach to improve the immobilization of DNA strands on gold, and might therefore help with the development of enhanced DNA sensors.

We carried out chemical purification of commercially available diamond nanoparticles by refluxing in aqueous HNO₃ and characterized the samples by spectroscopic and surface techniques before and after purification. As a first step in the preparation of electrodes for electrochemistry, we have electrophoretically deposited thin, highly uniform films of controlled thickness (1–8 μm) on silicon substrates using the purified diamond nanoparticles. These have been characterized by scanning electron microscopy (SEM). All films obtained were homogeneous in thickness and without macroscopic holes or cracks. Such structures could also be used in many other applications such as fuel cells or lithium batteries. We have performed cyclic voltammetry experiments with these electrodes. The voltammograms of diamond nanoparticles electrophoretically deposited on silicon indicate hydrogen evolution. This demonstrates that the material is useful as electrocatalitic support. This conclusion is supported by the cyclic voltammograms obtained using ferrycyanide (III) chloride and hexaamineruthenium (III) chloride complexes as redox probes. However, these redox probes showed very small peak currents. This behavior could be improved by doping the diamond nanoparticles with an impurity such as boron.

With its noteworthy physical and chemical properties, diamond is expected to find many applications in various industrial fields, particularly with the expansion of the new nanotechnologies. In order to optimise their use in these specific conditions, it is essential to better understand the very complex tribological behaviour of diamond coatings. This latest is studied from a macroscopic point of view, but essential facts which occur at a nanoscopic scale are still not well known. The mechanisms involved not only in the nucleation and growth of the diamond crystals, but also in the nanofriction of the coatings, must be understood. One way to reach this purpose is to analyse the crystals morphology and behaviour at a very small scale : atomic force microscopy (AFM) seems to be a suitable technique for this work.

The crystals morphology is initially studied in tapping mode; the first observations indicated that secondary growth happened on the facets. Experiments in contact mode are then carried out : the observed behaviours are different on a facet, on a crystal, or on a part of the coating. The load applied to the tip seems to have an influence too as the friction force increases when the contact load becomes higher; moreover, these variations are clearly linked to the topography of the scanned surfaces. The purpose of this nano-experimental work is to get information to better understand the friction properties of the diamond coatings at a nanoscopic scale, and to establish, if possible, a potential correlation between the behaviour noticed at the macroscopic scale, and the one obtained with AFM measurements.

With its high resistance, good hardness and electrical conductibility in the basal plans, graphite is used for many years in various tribological fields such as seals, bearings or electrical motor brushes, and also for applications needing excellent lubrication and wearreducing properties. But thanks to its low density, graphite is at the moment destined for technologies which need a reducing of the weight combined with an enhancement of the efficiency, as it is the case in aeronautical industry. In this contexte, the friction and wear of natural (named graphite A) and synthetic (called graphites B and C) powders were evaluated, first at the macroscopic scale when sliding against steel counterfaces, under various applied normal loads. Scanning Electron Microscopy and AFM in tapping mode were used to observe the morphological modifications of the graphites. It is noticed that an enlargement of the applied normal load leads to an increase of the friction coefficient for graphites A and C; but for the graphite B, it seems that a ''limit'' load can induce a complete change of the tribological behaviour. At the same time, the nano-friction properties of these powders were evaluated by AFM measurements in contact mode, at different contact loads. As it was the case at the macroscopic scale, an increase of the nano-contact load induces higher friction coefficients. The determining of the friction and wear mechanisms of the graphite powders, as a function of both their intrinsic characteristics and the applied normal load, is then possible.

We analyze the linear conductance of a semiconductor quantum wire containing a region where a local Rashba spin-orbit interaction is present. We show that Fano lineshapes appear in the conductance due to the formation of quasi bound states which interfere with the direct transmission along the wire, a mechanism that we term the Fano-Rashba effect. We obtain the numerical solution of the full Schrödinger equation using the quantum-transmitting-boundary method. The theoretical analysis is performed using the coupled-channel model, finding an analytical solution by ansatz. The complete numerical solution of the coupled-channel equations is also discussed, showing the validity of the ansatz approach.

Free-standing nanocrystals exhibit a size-dependant thermodynamic melting point reduction relative to the bulk melting point that is governed by the surface free energy. The presence of an encapsulating matrix, however, alters the interface free energy of nanocrystals and their thermodynamic melting point can either increase or decrease relative to bulk. Furthermore, kinetic contributions can significantly alter the melting behaviours of embedded nanoscale materials. To study the effect of an encapsulating matrix on the melting behaviour of nanocrystals, we performed in situ electron diffraction measurements on Ge nanocrystals embedded in a silicon dioxide matrix. Ge nanocrystals were formed by multi-energy ion implantation into a 500 nm thick silica thin film on a silicon substrate followed by thermal annealing at 900 °C for 1 h. We present results demonstrating that Ge nanocrystals embedded in SiO₂ exhibit a 470 K melting/solidification hysteresis that is approximately symmetric about the bulk melting point. This unique behaviour, which is thought to be impossible for bulk materials, is well described using a classical thermodynamic model that predicts both kinetic supercooling and kinetic superheating. The presence of the silica matrix suppresses surface pre-melting of nanocrystals. Therefore, heterogeneous nucleation of both the liquid phase and the solid phase are required during the heating and cooling cycle. The magnitude of melting hysteresis is governed primarily by the value of the liquid Ge/solid Ge interface free energy, whereas the relative values of the solid Ge/matrix and liquid Ge/matrix interface free energies govern the position of the hysteresis loop in absolute temperature.

The time-dependent approach is applied to the description of resonant tunnelling vertical transport accompanied by LO-phonon scattering in asymmetric double-quantum-well systems both with ideal flat and large-scale disorder interfaces. The square-law dependence of dissipative resonant tunnelling rate on the value of coupling matrix element V in the structures with flat interfaces has been found to be radically different from the linear dependence tunnelling rates on V in the structures with nonhomogeneous interfaces. As a result a substantial decrease in the effective tunnelling time in the case of nonhomogeneous interfaces is exhibited in compare with the case of structures with an ideal flat interface, particularly in weakly coupled structures. The physical reasons for the diversity of the functional dependence are discussed.

Final passivation planarization is achieved by optimizing the stack height and trench width for technologies that are sensitive to passivation planarization like image sensor processes. Deposition profiles obtained by using our topography simulator elsa (Enhanced Level Set Applications) predict a range of trench width, stack height, and the thickness of the deposited layers which lead to a sufficient planarization margin. Furthermore, these predictions enable design of trenches with a sufficient side wall and bottom coverage in order to guarantee a proper moisture seal.

Au adsorbed(Au-Si) islands are formed by the deposition of Au atoms on the fabricated Si(111) surface, on which size selected Si nanoislands have been constructed. The growth of the Au-Si islands is subject to the substrate temperature, Ts. At Ts < 270 °C, the surface structure on Au-Si islands shows the Si(111) √3 × √3-Au structure, and some Au atoms form hole-island pairs on the flat surface because the diffusion length of the Au atoms is too short to reach to the Si nanoislands (about 10 nm). At Ts > 280 °C, The diffusion length of Au atoms becomes larger than a mean distance between the Si islands. At Ts > 300 °C, The surface structure on the Au-Si islands shows the Si(111) 5 × 2-Au structure, and some of the islands grow along one of the ⟨ 0 1 ⟩ directions. The result means that the surface diffusion of Si atoms among the Au-Si islands is drastically enhanced, that hardly occurs at Ts < 270 °C.