Table of contents

The extended boundary condition method is used to calculate the scattering of a plane electromagnetic wave from a finite dielectric cylinder of circular cross section. Three applications are presented: the backscattering properties of ice-like rods in the microwave region are calculated and compared with existing experimental data; the polarisation ratio of forward scattered light is computed in order to analyse an optical system for fibre discrimination; the extinction spectrum of rod-shaped ionic crystallites in the infrared is calculated and interpreted in terms of the characteristic phonon modes.

The propagation of non-linear wave modulation on a non-linear coupled transmission line which consists of two LC ladder lines connected by intermediary capacitors are investigated theoretically. Following the procedure of the reductive perturbation method the authors show that the original discrete equations of the LC circuit can be reduced to two coupled non-linear Schrodinger equations. The possible solutions of these equations are presented.

A method is presented for the systematic design of single material prism anamorphs, and is illustrated by the derivation of a prism pair to provide an anamorphic expansion of two whilst having no displacement, no deviation and no dispersion.

The case of steady thermal conduction in cylindrical and spherical shells with exponential heat sources is analysed, with emphasis on the possible occurrence of the maximum temperatures within the shells. For the materials lead, steel, concrete and water, and under certain illustrative conditions, a comparison is made with the results for slab geometry, including an indication of the errors prevailing when slab solutions are used in cylindrical and spherical shells.

The reduced mobility and longitudinal diffusion coefficients of SF₃⁺ and SF₅⁺ in SF₆ have been measured with a drift tube mass spectrometer over the ranges 30-360 Td and 20-510 Td, respectively. The extrapolated zero-field reduced mobilities were found to be 0.651+or-0.009 cm² V^-1 s^-1 for SF₃⁺ and 0.591+or-0.006 cm² V^-1 s^-1 for SF₅⁺. A comparison of the present mobility data for SF₅⁺ with previous work carried out without mass analysis strongly suggest that the unidentified ions were SF₅⁺. No other data over the present range of measurement were found to be available for comparison.

Measurements of the number density of neutral metal vapour during vacuum arcs by laser-induced fluorescence (LIF) are disturbed by electronic collisions which depopulate the upper fluorescence level. To overcome this difficulty, the sinusoidal arc current was rapidly forced to zero which resulted in a rapid reduction of the collisional interaction. This is shown by measurement of the collisional transfer from the optically pumped 4²P_3/2 level to the neighbouring 4²P_1/2 level of copper. Measurements of the laser-induced fluorescence were performed shortly before and after the artificial current zero. Due to the reduction of the collisional interaction, the LIF signal after current zero rises by an order of magnitude above its value before the artificial current zero, reaches a maximum two microseconds after current zero and decays as the vapour disperses. The vapour density inferred from the maximum LIF signal is considered as an approximate value for the density before the artificial current zero. By forcing current zeros at preselected times during a 50 Hz sinusoidal half-cycle with 200 A peak current, a lower limit for the vapour density during arcing was obtained. The copper vapour density rises to a maximum value of 3.6*10¹⁸ m^-3 near current crest and drops to 5*10¹⁶ m^-3 at the natural current zero of the half-cycle. Afterwards it decays by about two orders of magnitude within 1 ms.

A channel-type model for RF and microwave discharges, operating under a local thermodynamic equilibrium (LTE) regime and sustained by travelling waves, is proposed. Such discharges are, as a rule, axially non-uniform. The channel model presented includes this feature. From the analysis that follows, two functions of the value of the heat flux potential at the axis (S_A) turn out to be necessary to determine the spatial structure of the discharge. These are L(S_A), the power dissipated per unit length of the plasma column, and alpha (S_A), the wave attenuation coefficient. From these, the spatial distribution S(r,z) of the heat flux potential can be obtained. Under LTE conditions, this is sufficient to determine the distributions of all plasma parameters of interest. As an example, the spatial structure of a nitrogen discharge sustained by a surface wave is calculated.

Methane plasmas excited at 25 kHz and 13.56 MHz used for a-C:H deposition have been studied by optical emission spectroscopy. At 25 kHz the emitted bands and lines, namely CH (431.4 nm), H (486.1 nm) and H₂ (463.4 nm), have been found to result from dissociative excitation of the CH₄ molecule under electron impact. It is supposed that the fast electron beam formed by the accelerated secondary electrons is predominant. In this discharge a correlation between the CH emission and the deposition rate is found. In contrast to the 13.56 MHz discharge the H_beta emission appears to result from both dissociative excitation from CH₄ and electron impact excitation of H atoms present in the bulk of the discharge. A correlation between the I_H/I_CH intensity ratio and the bulk electron density measured by double probes has been found. However, no correlation has been found between the emission intensities of various species and the deposition rates. It is thought that processes in the vicinity of the RF electrode on which deposition occurs are predominant.

A model of a discharge XeCl laser with one-dimensional spatial discharge description is considered. The densities of the components of the laser active medium and the lasing pulse are modelled in time and space in the direction transverse to the electric force lines. The results of the calculations of the laser plasma components and the lasing pulse spatial-time dynamics, as well as of discharge current and voltage, are compared with the measured ones. The influence of the electric field and pre-ionisation inhomogeneity on the spatial distributions of the components of the XeCl laser active medium is considered.

In order to understand better the mechanisms of an abnormal glow discharge in nitrogen, the results of spectroscopic measurements have been compared to those of Monte Carlo simulation. Measurements were performed on the space distribution of the 1 S^- and 2 S⁺ bands of the nitrogen molecule. With a model which does not take into account any current dependent alteration produced within the gas by the discharge, large differences appear between experiment and modelling. An improved model has been solved based on additional measurements of the discharge in its build-up phase and discharge change due to cathode cooling. Evidence is obtained that the local change in the distribution of the neutral molecules density induced by the variations of the gas temperature seems to be the most important factor explaining the difference between computed and experimental results for the space distribution of the emitted light. Investigation is required of the angular scattering cross section associated with collisions between electrons and vibrationally excited nitrogen, because of production of a high concentration of vibrational species within the discharge. Also, the density of nitrogen in the metastable A³ Sigma _u⁺ level seems to give a non-negligible contribution to the creation of nitrogen in the C³ Pi _u state. In any case, the gas modification induced by the discharge must be taken into account in modelling the abnormal glow discharge.

The theory of the positive column at moderate pressures in electron-attaching gases is examined for small attachment rates relative to the ionisation rate. It is shown that the negative (and positive) ions are confined to a channel in the centre of the discharge, by both computational and analytical approximation methods. Approximate expressions for the channel width and the eigenvalue which determines the electron temperature are derived.

A rate equation model has been constructed for the optogalvanic effect produced by tunable laser excitation from the neon 1s states in the positive column of a normal glow discharge. The model includes separate rate equations for all four 1s states and has been tested for the 594.5 nm (1s₅-2p₄), 614.3 nm (1s₅-2p₆) and 609.6 nm (1s₄-2p₄) transitions over a range of discharge conditions including pressures ranging from 1.5 to 8 Torr and currents from 0.5 to 10 mA. The authors' model includes 1s ground-state atom and electron collisional coupling processes and they have shown that electron transfer plays a dominant role in determining the magnitude and sign of the optogalvanic effect for these transitions. In the pure neon positive column they have shown that the observed sign change with current for the 609.6 nm line is due to the change in the magnitude of the electron transfer from resonance to metastable states relative to the resonant atom wall losses. Their results indicate that in general transitions which exhibit optogalvanic sign changes may be used as sensitive diagnostic indicators of collisional mixing processes in discharge plasmas.

The momentum transfer cross section of argon is deduced from experimental electron drift velocity data over the energy range from 0.02 to 100 eV. A method proposed earlier by Suzuki et al. (1989) which is improved by adding a minimising procedure of the fractional difference between calculated and experimental electron drift velocities, is used. In an E/N range below 0.1 Td, the electron drift velocity data of Robertson (1977) at a gas temperature of 89.6 K are analysed and the cross section for the low-energy region is deduced. The result shows that the Ramsauer-Townsend minimum is located at an electron energy of 0.23 eV with a magnitude of 9.35*10^-18 cm². It is found that the present result is in excellent agreement with the theoretically determined values of Dasgupta and Bhatia (1985) and that the characteristic energy calculated from the present cross section agrees very well with the measurements of Milloy and Crompton (1982). In an E/N range above 0.1 Td, the experimental electron drift velocity data of Nakamura and Kurachi (1988) and Kucukarpaci and Lucas (1981) are analysed to deduce the cross section for the high-energy region. In order to obtain consistency among the present momentum transfer cross sections, ionisation cross sections by Krishnakumar and Srivastava (1988) and excitation cross sections by de Heer et al. (1979), reference is made to the ionisation coefficient data by Kruithof (1940), Abdulla et al. (1981) and Ishizuka et al. (1987). It is found that the peak of the momentum transfer cross section is located at an electron energy of 10 eV with a magnitude of 1.5*10^-15 cm².

A further investigation of laser-induced electrical breakdown of molecular gases is presented. By means of a modified version of the Evans and Gamal electron cascade model (1980), the breakdown parameters of molecular oxygen at pressures between 7.6*10² and 3*10⁴ Torr irradiated with 10 ns pulse of Nd:YAG laser radiation ( lambda =1.064 mu m) are calculated. The results provide satisfactory evidence for the important role played by the attachment losses term on the breakdown phenomenon associated with the interaction of molecular oxygen with laser radiation. A study of the effect of this loss process on the electron energy distribution function and its parameters is also presented.

A technique of self-absorption along a plasma diameter is developed to measure triplet state densities along discharges presenting axial inhomogeneities. This technique is based on the fact that a transition line between triplet states has components of different oscillator strengths, which are thus differently self-absorbed. It has been developed to measure the 2³S and 2³P helium state densities of a helium surface wave discharge (at 2.45 GHz). The results are compared to ones previously obtained by the Hook method in a positive column.

Emission spectroscopy in a parallel plate capacitively coupled RF discharge has been studied in propane-argon mixtures. Two kinds of emission spectra were recorded. The overall discharge was studied without any spatially resolved measurement and different spatial regions of the plasma were viewed from the cathode to the glow region. Carbon, argon, gold, hydrogen atoms and a CH radical were observed. Special attention was devoted to the spatial variation of argon, hydrogen and the CH radical for the purpose of understanding the anomalous CH emission in the 'plasma dark space'. Various plasma excitations are evaluated and discussed.

The range profiles of Xe ions implanted in a silicate glass at energies from 50 to 400 keV have been studied by the Rutherford backscattering technique. The data obtained are compared with the calculated values based on Biersack's angular diffusion model (1981). The results show that the measured mean projected range is in good agreement with the calculated value, but a marked improvement in the range straggling fit is obtained after including the second-order energy loss.

A method is described whereby ion implantation profiles in amorphous materials may be accurately represented by Pearson frequency distribution curves. The type of Pearson distribution to be used depends upon the implantation conditions but it is shown that the three main types, I, IV and VI, together with the transition types II, III, V, VII and the Gaussian are all suitable representations. Previous attempts to fit Pearson curves to implantation profiles have often failed due to semi-infinite moments being used instead of infinite moments. This approximation is only valid when the surface concentration of implanted ions is negligibly small.

Transmission electron microscopy (TEM) was used to investigate the structural evolution of InP during 50 keV Si ion implantation at room temperature (RT) and during further in situ annealing. The authors describe a new thinning method to obtain reproducible, easily handled and strong samples exhibiting very thin and large areas. In situ TEM studies were performed during implantation at 80 keV up to approximately 3*10¹³ Si⁺/cm². The defect density and size as a function of ion fluence is reported. Amorphisation sets in above a threshold fluence of approximately 2*10¹³ Si⁺/cm². Further studies on implanted samples at various total fluences show that the whole implanted layer ( approximately 70 nm) becomes amorphous at approximately 10¹⁵ Si⁺/cm². Below fluences of approximately 2*10¹³ Si⁺/cm² in situ thermal annealing leads to complete recovery of induced defect clusters at T>or=500 K. The defect clusters induced by Si ion implantation anneal out during TEM observation at electron energies >or=100 keV, an effect which they ascribe to the low displacement energy of P atoms ( approximately 8 eV).

The authors present results which show the topography of the laser-induced periodic surface structures formed upon samples of germanium, which had been irradiated at a wavelength of 248 nm, and fused quartz irradiated at 10.6 mu m. Surface profiles are obtained from phaseshifting interferometry measurements. A slight modification to a theory which models the development of the surface contour during resolidification of a molten surface can be successfully employed to explain their observations upon germanium. To explain the profiles obtained on fused quartz they suggest that plasma oscillations at the surface may be involved.

The preparation and evaluation of colloidally dispersed gold/polymer composites was undertaken to provide an insight into the DC electrical conduction mechanisms operative in metal-filled polymers. Transmission electron microscopy showed that a segregated gold particle structure was present. It was shown theoretically that a significant enhancement in specimen conductivity should be achievable if the particle size ratio was allowed to increase. Of the two polymer matrices studied, the polyethylene showed an anomalous variation of volume resistivity with gold content, in comparison with the poly(methyl methacrylate) matrix. This difference was attributed to changes in spherulite size in the polyethylene when the submicrometre gold particles were added.

The effect of variation in the concentration of a dopant salt i.e. copper chloride, on the electrical conductivity of doped nylon-6 films has been investigated. The electrical conductivity of pure and doped films of nylon-6 doped with various concentrations of copper chloride (0.5% to 12.5%) is measured as a function of applied voltage and temperature. The plots of log I-log V for pure and doped films show that the current in both cases is space-charge limited. From these plots, the carrier mobility and the density of trapped carriers are calculated. It is observed that the mobility becomes maximum and the density of trapped carriers becomes minimum for a 1.25% doped film of nylon-6. Similar results are observed for current density and activation energy of the doped films.

The AC conduction in thin potassium iodide films in the range 5 Hz to 20 kHz has been studied for applied voltages between 0.4 and 1.2 V at room temperature. The universal dielectric response sigma =b omega ⁿ for AC conductivity is obeyed for all the applied voltages. Taking into consideration the linearity in the AC conductivity and the nature of the potassium iodide films, previous results on the transient electrical conductivity of thin potassium iodide films are analysed and resolved into two components, one of which is associated with ionic conductivity and the other with the Poole-Frenkel effect.

Photoconductive CdS:La films have been prepared by a chemical bath deposition technique. Photocurrent to dark current ratios of the order of 10⁵ are observed. Growth conditions are discussed as a function of deposition time and concentrations of flux and impurity La. Trap depths of the order of 0.59-0.72 eV are found to be effective.

The effects of surface preparation on CdTe-based thin film heterojunctions have been investigated through characterisation of ITO//p-CdTe and CdS/p-CdTe solar cells. The surface treatment methods include air exposure at laboratory temperature for several months, heat treatment, bromine-in-methanol etching, and bromine-in-methanol etching with subsequent hydrogen heat treatment. The authors have found that the behaviour of CdTe heterojunctions was significantly improved by the surface treatment of CdTe films exposed to air for several months at laboratory temperature prior to window material deposition. The stability of as-prepared cells has been considerably enhanced. Other methods of surface treatment seem to have insignificant effects on the improvement of subsequent heterojunctions. The explanations given for the improved performance of the solar cells are discussed.

The square-array model with infinite chains of contact is proposed to account for the dependence of electrical properties on frequency and fibre volume fraction in unidirectional carbon-fibre/epoxy-resin composites. The longitudinal AC conductivity, E vector parallel to fibre axis, decreases with increasing frequency due to magnetic flux change from neighbouring fibres and increases linearly with fibre volume fraction due to increment of specific fibre cross section within a volume element. A longitudinal permittivity of nearly unity for the frequency range of 1.7 GHz to 10 GHz, irrespective of fibre volume fraction, suggests that the composites can be considered as good conductors even at higher frequency. The three stages of increment and decrement with increasing frequency for transverse conductivity and permittivity, are ascribed to space charge polarisation. The increment of transverse AC conductivity with fibre volume fraction is ascribed to the increase of conducting channels.

A pulsed electric field induces transient birefringence in a suspension of anisotropic particles. The rate of decay of the birefringence depends strongly on the particle size via the rotary diffusion coefficient, D, of the particles. A more analytical method has been developed in which values of D, obtained from the initial slope of the post-field decay for a range of applied pulses of the same low electric field strength, but for continuously decreasing pulse durations Theta , are analysed to yield size distributions for the dispersed particles. By adopting a least-squares fitting and smoothing procedure, this electro-optical method is shown to handle arbitrarily multimodal distributions. The method is appraised via regenerated theoretical data for a mixture of submicrometre spheres and for experimental data on suspensions of lozenges of polytetrafluoroethylene and iron oxide spheroids. The method is suitable for submicrometre-sized particles.

Thermally stimulated depolarisation current measurements on hydrated Iysozyme powder in the temperature range 77-300 K and water content range 0.07-0.29 g water/g dry protein show a broad low-temperature peak in the range 100-60 K and a complex high-temperature band in the range 160-300 K. Four dispersions were found to contribute to the high-temperature band, the alpha ₂-dispersion, the alpha -dispersion, the Omega -dispersion and a 'new' dispersion. The alpha -dispersion and the new dispersion occurring in the same temperature range were studied in detail. The new dispersion appears for water contents higher than about 0.15 and it shifts to lower temperatures with increasing water content while its magnitude rapidly increases. Its characteristics help one to identify it with a dispersion observed by Careri and co-workers (1985,6,8) on hydrated Iysozyme powders in the frequency range 10 kHz-10 MHz at 302 K and attributed to percolative proton transfer along threads of hydrogen-bonded water molecules on the surface of single protein macromolecules. The activation energies of the alpha -dispersion and the new dispersion were determined. Both dispersions are characterized by distributions of relaxation times and activation energies.

Infrared spectra of cholesteryl oleyl carbonate, cholesteryl nonanoate and their mixtures in the C-H stretching region have been examined in the crystal, cholesteric liquid crystal and isotropic liquid states. Changes in the intensities of the bands are attributed to the decoupling vibrations at phase transitions. A band at about 2950 cm^-1 appeared in all crystal spectra, decreased in intensity at the cholesteric transition, but disappeared in the isotropic state owing to the combination mode. This indicates that the local order of the cholesteric liquid crystals lies between that of a solid and that of an isotropic liquid. Vibrational spectra of the mixed systems show that two components are completely miscible in the crystal, cholesteric liquid crystal and isotropic states.

The thermoluminescence (TL) response of pure Norwegian quartz as a function of irradiation temperature (T_irr) and dose has been investigated. The TL response of the (150-230 degrees C) and (230-350 degrees C) glow curve intervals shows a strong dependence on T_irr between 77 and 373 K in the dose range from 54 to 8.4*10⁴ Gy. Both glow curve intervals also show temperature dependent dose response properties. The 150-230 degrees C interval is supralinear from the lowest dose (54 Gy). Its maximum supralinearity factor appears at T_irr=293 K. The 230-350 degrees C interval shows sublinear behaviour below T_irr=193 K, while at T_irr>or=273 K it shows the well known dose response curves. Its maximum supralinearity factor appears at T_irr=323 K. The linear response is extended up to 460 Gy at T_irr=273 K and falls to 80 Gy at T_irr=373 K.

It is shown that, assuming first order kinetics and a frequency factor s(T) given by s(T)=s₀T^a with -2<or=a<or=2, it is impossible to determine the value of a from any combination of thermally stimulated luminescence (TSL) measurements alone, provided E/kT_m is greater than about 20 (E is the activation energy, T_m is the temperature of the glow-curve intensity maximum). This is contrary to the conclusions of Keating (1961). Thus the data can be fitted equally well, within the limits of the best experimental accuracy presently attainable, by several physically reasonable (E,s₀,a) combinations. The usual assumption of a temperature-independent frequency factor can lead to E value errors as high as 10% at E/kT_m=20, decreasing to 3% at E/kT_m=80. The same is true for second-order kinetics, provided E/kT_m exceeds approximately 25. Since determination of the index a by other methods presents formidable experimental difficulties, and determination of E by other methods introduces errors which would almost certainly exceed those arising from the assumption a=0 in TSL measurements, it follows that the accuracy of E values is limited to about 3% in nearly all samples.

The authors used a PbO thin film incorporated in a trilayer anti-reflection structure for write once and read many (WORM) optical storage. The medium, both with and without an in-contact protective overcoat, showed multiple levels of reflectance change after low-power laser writing at 6328 AA wavelength. The multiple levels of reflectance changes correspond to multiple phase changes due to the PbO film going through PbO (massicot), Pb₃O₄ (minium), PbO_1.37, PbO (litharge), PbO (massicot) phases and then melting in the temperature range up to 700 degrees C. There is a possibility of formation of PbWO₄ phase when the absorber layer is tungsten.

Mass and energy analyses of ions emitted from an AuSi eutectic alloy liquid metal ion source (LMIS) were carried out using a tandem double-focusing mass spectrometer. In the investigated ion current range between below 1 mu A and 10 mu A a great variety of molecules and clusters were detected. The field strength at the apex of the Taylor cone was estimated from post-ionisation probability to be 20 V nm^-1 for silicon ions and 30 V nm^-1 for gold ions at 10 mu A emission current. The energy spread of different ion species depends on the charge-to-mass ratio and on the total extracted ion current. For the ion current dependence of the energy spread a nearly two thirds power dependence was obtained. The energy width varies between 10 eV and 100 eV for Au ion species and between 10 eV and 20 eV for Si ion species. The energy deficit decreases with increasing ion current for Au and Si ion species. The authors assume a decrease of the field-dependent activation energy of field evaporation together with growing asymmetry in the energy distributions.

New chalcopyrite quaternary compound CuAl_xIn_1-xSe₂ (0<x<1) has been obtained. X-ray diffraction measurements have been performed and lattice parameters have been found. Absorption in the region of the energy gap and photoconductivity has been investigated. Dependence of the energy gap on composition has been determined and possible applications of the compound in photovoltaics are discussed.

Highly orientated films of the transition metal dichalcogenides 2H-MoS₂, 2H-WS₂, 2H-TaS₂ and 3R-NbS₂ have been prepared using a suspension of the powders in water. The layered material is collected at the water/organic interface by shaking the suspension with a water-immiscible organic liquid. The films are spread spontaneously over a wet substrate using the Marangoni effect. The electrical resistance of spread films of NbS₂ increased on exposure to humidity, contrary to conventional behaviour. Rapid, reversible incorporation of water into the spacing between the basal planes of the layered platelets and at platelet edges is believed to be the cause of this curious effect. The response of the other dichalcogenide films to humidity was not significant.

Barium titanate ceramics exhibiting the positive temperature coefficient of resistance (PTCR) effect were prepared with donor concentrations ranging from 0.05-1.8 at.%. The resistance of the various samples (normalised to give the specific resistance of a unit area of grain boundary rho _L in order to eliminate the effect of the observed reduction in grain size with increased donor concentration) was measured in the vicinity of the ferroelectric transition temperature T_c. Arrhenius plots of rho _L against (T- theta )/T, where T is the absolute temperature and theta is the Curie point, were then obtained for T>T_c. The plots were found to be linear up to a few degrees below the temperature corresponding to the maximum value of rho _L, in agreement with the well known Heywang model. The potential barrier heights, calculated from the slopes of the Arrhenius plots, were found to be similar for samples containing 0.1-1.4 at.% ( approximately 0.2 eV at 150 degrees C) and greater in more heavily doped specimens (0.4 eV at the same temperature). However, the Arrhenius plots belonging to samples containing 0.05 at.% were linear for a small temperature range since the PTCR jump was very small and consequently it was not possible to calculate the potential barrier height with any accuracy.

The temperature and anharmonicity effects on the thermodynamic properties of alpha -helical protein, which is regarded as a quasi one-dimensional H-bonded Toda lattice, are investigated at both low and high temperatures by using a thermodynamic Green function technique based on field-theoretic methods. The specific heat of alpha -helical protein at low temperatures is in agreement with the experimental results now available.

One-shot NMR imaging with a very short data acquisition time ( approximately 20 ms) is used to reveal the structure of a turbulent equilibrium puff in a transitional pipe flow. Longitudinal vortices in the downstream region of a puff are very clearly visualised in the NMR images. The structure of a puff derived from the images agrees with that suggested by a flow visualisation experiment done previously. The present study demonstrates that one-shot NMR imaging is a very powerful tool in visualising large-scale coherent structures in turbulent flow.

The fluorescence from high-pressure argon plasmas (1-30 bar) has been excited with an intense flash X-ray device. For the first time a spectrum from 110 to 700 nm has been recorded under such conditions. The spectra obtained in the UV-VUV were very similar to those recorded with alpha -particle excitation at equivalent pressures. The dominant features were the so-called second and third continua of argon. The visible fluorescence was found to be negligible in comparison with the VUV continua.

A new strategy for building conducting LB films is presented. The conducting behaviour is obtained by mixing in the same layer amphiphilic and semi-amphiphilic TCNQ derivatives. The optimum conductivity (6.9*10^-3 S cm^-1) is obtained for hybrid stacks of TCNQ in which the average electronic charge is -0.33.

Copper films, deposited on glass, are oxidised in air under irradiation by means of a scanned Ar⁺ laser beam. It appears that, for fixed scanning velocity, the optical characteristics of the resulting oxide films depend on the laser beam power density and the thickness of the initial copper films.

Reports the observed variation of electrical resistivity with thickness of tin oxide films grown by spray pyrolysis. An explanation for the observed variation is also given.