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Many optical-based plasma diagnostic techniques require electron-impact excitation cross sections. In recent years, a considerable number of new results have become available for excitation of rare-gas atoms from both the ground state and metastable states. Using relatively simple techniques these cross sections can be combined with plasma emission measurements to extract many useful plasma parameters such as the electron temperature. Many of the limitations of simple plasma emission models such as the corona model can be overcome by using cross section measurements to select what particular emission lines to use in the analysis.

We found that, although alpha'-cyano-4'-nitro-4-N, N-dimethylaminostilbene has larger hyperpolarizability than that of conventional 4'-N, N-dimethylamino-nitrostilbene, the addition of the cyano group makes it much more easy to photo-isomerize, thus destroying the molecular ordering in poled chromophore doped polymers. Experimental evidence was obtained by monitoring the second-harmonic generation intensity, UV–Vis absorption spectrum, and FTIR spectrum. The photo-isomerization reaction process was monitored by optical pump induced absorption anisotropy measurement. Comparisons with the behaviour of a azobenzene dye are also made.

We demonstrate the thermally activated degradation pathways of the ITO-coated glass/CuPc (copper phthalocyanine)/NPB (N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine)/Alq₃ (tris(8-hydroxyquinoline aluminium) device by using variable temperature tapping mode atomic force microscopy. It is observed that the initially morphological change of the top Alq₃ surface occurred at about 75°C. NPB gradually erupted from the Alq₃ capping layer at 120°C. The NPB layer and the Alq₃ layer were gradually mixed with increase in temperature from 130°C. Simultaneously, de-wetting took place at the interface of CuPc/NPB. Using conducting atomic force microscopy we see that morphological change in the device leads to a variation in current–voltage characteristics of the degraded ITO/CuPc/NPB/Alq₃ device. The results should shed light on the thermally activated degradation mechanisms of organic light-emitting diodes.

We use CO₂ laser-induced thermoluminescence to measure radiation dose deposition profiles in thin films. Films of various thicknesses, ranging from 10 to 90 µm, are deposited on a substrate and irradiated. The deposited dose is read out at a high heating rate so that strong signals can be obtained even from thin films. Our experiments use LiF films and ⁹⁰Sr and ²⁴¹Am radiation sources. This method allows nondestructive measurement of deposition profiles directly in thin solid films.

The synthesis of a high photoluminescence efficiency (88%, compared with tris(8-hydroxyquinoline)(Alq₃)) organic material 9,9-Dibutyl-N,N,N,N-tetraphenyl-9H-fluorene-2,7-diamine (DTFD) via Ullmann condensation was reported. Exiciplex emission of the ITO/DTFD/2,2-[1,2-phenylenebis(oxy)]bis(N,N-diphenylacetamide)/Alq₃/LiF/Al device was observed and the peak wavelength of the emission was measured to be 480 nm, which belongs to the blue region. A turn-on voltage as low as 4 V and maximal brightness as large as 400 cd m⁻² were measured. The electroluminescence spectrum was observed to be blue-shifted with increase in applied voltage.

The structural changes in P⁺ ion-implanted and rapid thermally annealed Si(100) wafers have been studied using spectroscopic ellipsometry (SE). The P⁺ ion implantation was performed at 150 keV with a fluence of 2 × 10¹⁵ cm⁻² at room temperature. The rapid thermal annealing was carried out at 600°C in a dry N₂ atmosphere for durations between t = 5 and 100 s. A model dielectric function (MDF), which was developed for modelling the optical properties of perfectly crystalline semiconductors, has been applied to study the optical properties of the ion-implanted and annealed layers. The experimental SE data have been successfully interpreted by the MDF with properly changing the critical point parameters from the perfectly crystalline values. The recrystallization is found to occur from an amorphous/crystalline interface with a rate of ∼340 Å s⁻¹ at the initial annealing stage (t ⩽ 5 s) and ∼13 Å s⁻¹ at the subsequent annealing stage (t > 5 s). The amorphous/crystalline phase transition is also found to occur at t ∼80–90 s. SE has been demonstrated to be an easy, fast and nondestructive technique, which can be used to assess important structural parameters in ion-implanted and annealed layers.

With increasing demand for micro-/nano-polymeric components, micro-/nano-moulding using a nano-stamper has received much attention. When the features of the patterns on the stamper become smaller, the moulding temperature needs to be increased for improving the ability of the stamper to replicate quality polymeric components using nano-moulding. However, if the temperature is too high, the adhesion between the stamper and the polymer may deteriorate the surface quality of the moulded part, excessively wearing down the stamper surface. In this study, an experimental method is presented to analyse the temperature dependence of the anti-adhesion property between a stamper with sub-micron patterns and the polymer. For the analysis, the contact angle between the stamper and the polymer was measured at the temperature of the actual nano-moulding process, in which the stamper is heated above the glass transition temperature of the polymer. The effects of the moulding temperature and the contact angle on the surface quality and the replication quality of the moulded substrates were analysed experimentally.

In this paper, we explain the physical reasons for the enhancement of near-UV and visible emissions from a low-pressure mercury–argon discharge under pulse drive conditions. The conditions of operation that maximize the enhancement of near-UV and visible radiation, including the effect of the buffer gas, are investigated. We show that for a pulsed discharge, electron–ion recombination followed by cascade radiative transitions is the process responsible for most of the 365 nm emission and that argon with a small admixture of krypton is the buffer gas composition that leads to maximum radiative emission due to near-resonant energy transfers to mercury high-lying levels.

In sputter magnetrons the electrons emitted from the target, the so-called secondary electrons (SE), can be recaptured by the target. As a result, not all emitted SE will interact with the discharge gas. The effective gas interaction probability (EGIP) is the probability that an emitted SE interacts with the discharge gas, and thus is not recaptured by the target. To calculate the EGIP an analytical model is developed. The model is verified by comparing its results with those of a Monte Carlo model.

The EGIP of an individual SE is strongly, and in a complex manner, dependent on the electric and magnetic field to which the electron is subjected and on its initial starting conditions. Therefore, it is useful to introduce the average EGIP of the discharge which is a weighted average of the individual EGIP values. The influence on the EGIP of different parameters, such as the initial energy of the SE, the electron reflection coefficient and the electric and magnetic field is discussed. For typical discharge conditions at a pressure of 0.5 Pa values for the average EGIP in the range of 0.25–0.35 are found. This means that the recapture probability lies typically between 65% and 75%, showing that it is necessary to take into account this process to accurately model and simulate the magnetron discharge.

The evolution of the system sheath/presheath has been investigated experimentally. The ions of maximum kinetic impact energy ε_max collected at the surface of an orifice electrode are thereby used as test particles. The orifice electrode cylindrically surrounds an Ar plasma dc-excited in a parallel plate configuration, at a pressure of 10.8 × 10⁻² mbar. A negative rectangular low-voltage pulse is applied to the orifice electrode. The resulting time dependent ion current is extracted and investigated. A combination of pulse length and retarding field variation allows one to determine ε_max and its time dependence.

The time evolution of ε_max is measured during sheath and presheath formation. Sheath relaxation is investigated by applying a voltage pulse to an already existing sheath/presheath system in front of the orifice electrode. This is compared to the evolution of a new sheath starting from the sheath-free electrode. Probe measurements confirm that the presheath is formed within the last part of energy increase of ε_max over an energy value of kT_e/2.

The bulk gas temperature in a 30% N₂/70% Ar, short-pulsed (<15 ns, FWHM) dielectric barrier discharge (DBD) was determined from the time-resolved diode-laser absorption of metastable Ar 4s' [½]° and the rotationally resolved 1st Negative and N₂ 2nd Positive plasma emission. The gas temperature, derived from the and N₂ emission spectra, was determined from contour analysis of individual vibrational bands in the 1st Negative and 2nd Positive systems, while the temperature under the same discharge cell conditions was determined from the Doppler width of the metastable Ar absorption spectrum. The gas temperature determined for a low average power DBD at pressures of 10, 30, and 100 Torr and pulse repetition rates of 0.5–30 kHz was found to be slightly above room temperature (∼350–400 K) and did not vary with pulse repetition rate.

The experimental work reported here is devoted to the temporal behaviour of a mono-filamentary dielectric barrier discharge in pure argon, from 100 to 700 Torr. A sinusoidal voltage supply is used, its frequency ranging from 10 to 90 kHz. An anode avalanche followed by a cathode streamer as well as the spatial stability of the micro-discharge is clearly seen in successive 3-ns snapshots in the visible range. Near the cathode, its diameter is about 0.2 mm, at 400 Torr. The electrical characteristics of the discharge are also evaluated, in particular the breakdown voltage and the energy deposited in the micro-discharge. The light output in the vacuum ultraviolet range is essentially due to the second continuum of argon, centred at 130 nm. The kinetic study of this continuum shows that primary excitation of the lowest argon atomic 4s and 4s' states is practically achieved after 120 ns since beyond that time the luminescence decay of the second continuum is fairly described by only two exponential terms. So collisions between excited states, electronic collisions, and recombination of ionic species do not contribute significantly to this luminescence, after 120 ns. Surprisingly, we do not observe the contribution of the Ar(³P₁) resonant state in the production of the argon excimers. The radiative lifetime of the Ar₂[1_u(³P₂)]_{low v} excimer ((3.18 ± 0.03) µs) and the three-body rate constant relative to the decay of the Ar(³P₂) metastable state ((13.2 ± 0.9) Torr⁻² s⁻¹) leading to the formation of Ar₂[1_u(³P₂)], are estimated. These results are consistent with those found from the literature. A simple kinetic scheme is proposed for times later than 120 ns.

Thin oxide films are deposited from tetramethoxysilane in an inductively coupled oxygen glow discharge supplied with radio frequency power. The chemical bonding states of deposited films are analysed by Fourier transform infrared spectroscopy. The deposition rate and optical properties are determined from spectroscopic ellipsometry. Capacitance–voltage measurements are performed in MOS capacitors to obtain the electrical properties of the deposited films. With these tools, the effects of the substrate bias power and the oxygen mole fraction in the gas on the properties of the film are investigated. The refractive index first decreases with an increase in the oxygen mole fraction, and then increases again, showing a behaviour opposite to that of the deposition rate. The deposition rate increases with increasing substrate bias power and then saturates, while the refractive index increases slightly with an increase in the substrate bias power. The fixed oxide charge density decreases with increasing oxygen fraction and with increasing substrate bias power, while the interface trap density increases with increasing oxygen fraction and with increasing substrate bias power.

Bi-2212 precursor films were deposited on both sides of polycrystalline Ag tapes by electrodeposition. After a melt-quench and annealing process, highly c-axis textured Bi-2212 films were obtained on Ag tapes. The full-width at half-maximum of the (008) rocking curve was around 5.8°, and scanning electron microscopy measurements indicated that the Bi-2212 films had a dense and melted plate-like structure. The superconducting transition temperature, T_c (zero resistance), was about 82.4 K, and a critical current density, J_c (75 K, 0 T), of 29 kA cm⁻² was observed in transport measurements. A J_c (4.2 K, 0 T) value of about 0.3 MA cm⁻² was calculated from magnetization measurements. The mechanism of formation of the Bi-2212 superconductor in the melt-quench and annealing process is discussed.

The distribution of an ion current density on a substrate with a discontinuous film consisting of islands of dimension 25–100 nm was studied numerically. It was found that the ion current distribution is highly non-uniform and islands of the discontinuous film are enclosed with sharply defined zones where the current density is very low. The total area of low current zones reaches 30–50% of the substrate area, depending on the voltage applied to the substrate. The ratio of island radius–low current zone width depends on the island size and equals approximately 1.0 for large islands and 0.5 for small islands. It is shown that the island distribution function may be controlled by bias voltage variation.

Oxygen-free TiC_xN_y films have been prepared using the reactive ion beam mixing technique. A 400 Å thick film of Ti was deposited on a float glass substrate and then coated with a 80 Å Carbon layer. These bilayer structures were irradiated by 4 keV nitrogen ions for different nitrogen doses. In situ core level x-ray photoelectron spectroscopy (XPS) measurements were carried out to characterize these films. XPS results revealed that after nitrogen ion bombardment a sufficient amount of nitrogen was introduced in the Ti/C bilayer. On the basis of the binding energy parameters of the Ti 2p, N 1s and C 1s core levels and their shifts from the elemental position, the formation of compound TiC_xN_y near the surface is confirmed. The XPS result of formation of TiC_xN_y is supported by x-ray diffraction measurements.

Zirconium oxide thin films are deposited at low temperatures (lower than 350°C) using a filtered cathodic vacuum arc. Film structure, surface morphology and optical properties are systematically investigated. The results show the dependence of the properties on substrate temperature. Film structure develops from amorphous to polycrystalline at 150°C. Further increasing the temperature to 230°C leads to the preferred orientation along [−111] and [−221] directions, and at 330°C along only one observed preferred [−111] direction. In addition, crystal size in all the crystallized films is within 15 nm. The increase of substrate temperature results in an increase of surface roughness from room temperature to 230°C, but to a slight decrease at 330°C. The variations in optical properties, such as optical constants and E_g, with substrate temperature are correlated to the changes in film microstructure.

Nd₄₈Al₂₀Fe₂₇Co₅ bulk metallic glass (BMG) was prepared in the shape of rods 3 mm in diameter by suction casting. In contrast to the previously reported hard magnetic Nd–Al–Fe–Co BMGs, the Nd₄₈Al₂₀Fe₂₇Co₅ as-cast rod exhibits a distinct glass transition, multi-step crystallizations in DSC traces and much lower coercivity. The glass forming ability as well as the kinetics of the glass transition and crystallizations of the Nd₄₈Al₂₀Fe₂₇Co₅ as-cast rod have been studied. The magnetic properties of the alloy were investigated in comparison with Nd₆₀Al₁₀Fe₂₀Co₁₀ glass forming alloys.

A scaling analysis for momentum and heat transport in the laser-induced melt pool of ceramic materials has been carried out to predict the flow velocity and velocity boundary layer thickness at the melt surface. Compared with analyses available in the literature for momentum and heat transport in the melt pool formed by other high energy density beams, the present scaling analysis has more appropriately incorporated the volumetric heating source in the energy equation and quantified the relative amounts of laser energy consumed by thermal diffusion and by the traverse of the workpiece. The scaling predictions have been assessed by comparison with numerical results of a case study obtained by the present authors, and good qualitative agreement was observed.

We theoretically investigate the dielectric properties of a granular metal–dielectric composite with negative effective permittivity capable of creating band gaps in a wide range of frequencies. When the effective permittivity of the composite is negative, the electromagnetic (EM) waves will be reflected. The results show that for a given volume fraction lower than the percolation threshold, the effective permittivity of the whole composite can be negative for a certain range of frequencies during which the EM waves are forbidden to propagate in the composite. Considering the different geometrical structure, we discuss the possibility of artificially preparing materials with negative permittivity that would create frequency band gaps. Furthermore, we also investigate a metal–dielectric system with non-spherical inclusion, which leads to multiple frequency gaps for the EM waves.