Table of contents

A pulse-excited YAG laser beam and two rectangularly modulated CW YAG laser beams transmitted through optical fibres were collimated and condensed to a focal point by combining optics developed to increase laser power for materials processing. We found that the cross sectional shape of SUS304 penetration is strongly dependent on the delay time between incidence of the pulse-excited YAG laser beam and that of the rectangularly modulated CW ones. We obtained a deep penetration welding with half the power density of simultaneous irradiation with both types of laser beam using the combining optics, when we irradiate with the pulse-excited YAG laser beam just after a keyhole has been formed by the previous irradiation with CW YAG laser beams.

The effect of incident radiation in the ultraviolet-to-visible light transition region on the transmittance properties of thin zinc oxide layers deposited electrolytically on ITO-coated glass substrates has been studied and the optical band gap - layer thickness relationship has been established. The results indicate the viability of a low-temperature deposition process yielding transmittance properties comparable to those exhibited by conventionally obtained ZnO layers.

We present a selective review of electronic structure calculations for ferromagnetic transition metal alloys. This is work based on the spin density functional theory of the inhomogeneous electron gas which we also discuss briefly. These calculations can be used to provide estimates, from `first principles', of the alloys' characteristic properties such as the saturation magnetization, , and the exchange, A, and anisotropy, K, constants as well as their Curie temperatures, , which are all important quantities for the micromagnetic modelling of these materials. The electronic reasons for the simple structure of Slater-Pauling curves of versus the number of valence electrons are given. Anisotropy constants, K, can be evaluated only when relativistic effects upon the electronic motion are included. We review the theory of finite-temperature metallic magnetism and highlight how the electronic structure of metals and alloys in their paramagnetic states can still exhibit a local spin polarization originating from the `local moment' spin fluctuations which are excited as the temperature is raised. Finally we show how an alloy's magnetic state can sharply influence the types of ordered arrangements that the atoms form and conversely how the type of compositional structure can affect and K. We include a discussion of how the compositional structure can be described in terms of static `concentration waves'. We illustrate the approach by outlining our recent case studies of two iron-rich alloy systems, and .

The scattering of the thermal waves on buried small thermal resistances is theoretically studied in the framework of conductive thermal modelling of the coupling between a SThM probe and a sample. Lateral resolutions for the amplitude and phase of the probe's ac thermal response are obtained. The modelling, using an iterative method, goes beyond the usual first Born approximation results. Technically, the ac temperature field in the entire geometry is expressed in terms of two-dimensional plane wave spectra which permit direct use of fast Fourier transform algorithms. The various analytical results are easily obtained via a multilayer treatment of the probe and of the sample.

A simple numerical method allowing one to simulate the imaging process in the non-contact mode of the scanning force microscope in the case of a pyramidal tip interacting with a corrugated surface is presented. The attractive van der Waals and repulsive forces are described by a Lennard-Jones-type potential in order to study the image of nanostructures in the constant-height and constant-force-gradient modes. The influence of the tip's shape is demonstrated and the notion of resolution is discussed for both modes. We also analyse the consequences of the chemical natures of the nanostructures and the substrate for the image.

This paper presents results of normal hardness, plasticity index and elastic modulus for a selection of organic polymers (a poly(methylmethacrylate), PMMA, a poly(styrene), PS, a poly(carbonate), PC, and an ultra-high molecular weight poly(ethylene), UHMWPE) obtained using the contact compliance method. The paper describes in detail the dependence of the imposed penetration depth, the maximum load and the deformation rate upon the hardness and elastic modulus values for these polymeric surfaces; typical penetration depths range from about 10 nm to m where the imposed loads are less than 300 mN. The results show a considerable strain-rate hardening effect for the present systems and possibly a peculiarly harder response of these materials at the near-to-surface (submicron) layers. The paper includes considerations of a practical nature which are drawn in order to overcome some intrinsic limitations of this technique when it is used for polymeric surfaces, especially for a creeping phenomenon which may be observed at the incipient unloading experimental segments. The appropriateness of using a tip calibration constructed upon hard substrates when indenting polymers is reviewed at the conclusion of the paper.

Films of Ni-7 at% V, Pt, Pd, and , each approximately 100 nm thick, were magnetron-deposited and interposed between about 250 nm thick copper overlayers and single-crystalline substrates. The samples were then annealed in vacuum up to C. The performance of the metal and the tantalum-silicon-nitride films as diffusion barriers for in-diffusion of Cu and out-diffusion of Bi and Te was evaluated by 2.0 MeV backscattering spectrometry and x-ray diffraction. The Ni-7 at% V, Pd and Pt films all fail to prevent interdiffusion of Cu and after a few hours of annealing at C. However, the barrier preserves the integrity of the contact after C for 50 h and C for 1 h anneals. These results confirm the superior characteristics of the metal-silicon-nitride films as diffusion barriers.

Results of studies on the effect of inorganic overlayers on the long-term stability of discontinuous silver films deposited on softened poly(2-vinylpyridine) (PVP) substrates are reported in this paper. Discontinuous silver films were evaporated onto PVP-coated glass substrates held at 425 K in a vacuum of Torr. The films were coated with overlayers of O, and prior to exposure to the atmosphere. The stability of the films against exposure to the atmosphere was studied by monitoring the resistance during and after exposure to the atmosphere. The stability was monitored for a period of 120 days and the film's resistance had stabilized by 30 days. Results indicate that overlayers improve the stability considerably and seems to be the best passivator, closely followed by . However, compared to O, gives better protection even with a smaller overlayer thickness. A stable discontinuous film with a gauge factor of about 30 could be prepared by depositing silver onto softened PVP passivated by an overlayer, after 30 days of ageing.

thin films have been prepared firstly by an atmospheric-pressure metal-organic chemical vapour deposition technique. Smooth and polycrystalline films with uniform composition were deposited onto silicon substrates at a substrate temperature of for 1 h and the fully (001)-textured films were obtained with a rapid thermal annealing process thereafter at a temperature of for 60 s. The prepared films exhibited good structural, dielectric and ferroelectric properties. The measured dielectric constant and dissipation factor at a frequency of 100 kHz were 107 and 0.066, respectively, for a thick film annealed at for 60 s. The frequency dependences of the dielectric constant and the dissipation factor were also investigated. The ferroelectricity of the films was confirmed by recording P-E hysteresis loops with remnant polarization and coercive field values of and , respectively. The Curie temperature of the films was found to be 378 K. The influence of stress on the physical properties of the films was investigated.

Cathodoluminescence (CL) measurements were carried out on ZnSe/GaAs heterostructures grown by metal-organic vapour-phase epitaxy, partly with different pre-growth treatments. The influence of structural defects on the luminescence properties of ZnSe epilayers both above and below the experimentally obtained value of the critical thickness for strain relaxation were studied. The CL results combined with scanning transmission electron microscopy demonstrate that there is a correlation between structural defects and the deep-level emission at around 580 nm named the SA emission. In addition, a strong influence of the pre-growth treatment on the crystalline quality of epilayers of ZnSe was observed.

The magnetic and magnetoelastic properties of have been investigated. The stable single Laves phase is synthesized at ambient pressure for . The successful formation of this Laves phase can be ascribed to the strong Ce 4f bonding. Spin reorientation is observed around 150 K for Nd stoichiometric concentrations above 0.2. The lattice parameter, Curie temperature, low-temperature saturation magnetization and room-temperature anisotropic magnetostriction all increase with the Nd concentration. This indicates that the effect of the Ce ion is only dilution of the magnetism. is ferromagnetic with an estimated magnetic moment of per formula unit, a Curie temperature of 589 K and a room-temperature magnetostriction coefficient of 420 ppm. The largest saturation magnetostriction 320 ppm, is obtained at x = 0.2. No apparent evidence of Ce ions changing their valence was observed.

Amorphous ribbons of have been stress annealed in order to study the influence of magnetostriction on the magneto-impedance effect and its behaviour with applied tensile stresses. Magnetostriction is shown to be an important parameter that can be used to regulate the magneto-impedive response, as well as permeability and induced anisotropy. The amorphous ribbons change their saturation magnetostriction constants depending on the annealing parameters, between and and exhibit high values of the sensitivity to the applied magnetic fields in the magneto-impedance measurements, up to in the unstressed state and up to in the case of applying a 130 MPa tensile stress, at a frequency of 1 MHz.

The effect of substituting small amounts of Si for Fe and Co on the structure and magnetic properties of arc-melted ( and Co) compounds were studied by means of x-ray diffraction and magnetization measurements. X-ray diffraction study of indicates that the samples are single phase with the rhombohedral -type structure. The substitution of Si for Fe or Co leads to an approximately linear decrease in the unit cell volume. The saturation moment at 1.5 K decreases linearly with increasing Si concentration, being an approximately linear rate of about per substituted Si for and about for . The Curie temperature of is found to increase with increasing x from 476 K for x = 0 to 572 K for x = 3; however, of shows a monotonic decrease from 1213 to 651 K as x increases from 0 to 3. X-ray diffraction measurements of magnetically aligned powders show that the compounds with x = 0-3 have an easy-plane type of magnetic anisotropy. The easy magnetization direction of compounds changes from basal plane to c-axis with increasing Si concentration. The samples with x = 2 and 3 exhibit uniaxial anisotropy at room temperature.

The fundamental optical and magneto-optical (MO) constants of high-quality, rf magnetron sputtered, thin film DyGa have been determined throughout the optical region of the spectrum (-900 nm). These constants have been used to design trilayer structures for the enhancement of the polar Kerr effect in the wavelength range -500 nm where the optical absorption of the garnet material changes rapidly and the potential for MO enhancement increases. Trilayer structures have been fabricated and their optical and MO spectral performance compared with theoretical predictions.

The spatial relaxation of the electron distribution function (EDF) in uniform and spatially periodic electric fields is considered. The analysis is based on the Boltzmann kinetic equation containing spatial gradients and operators of elastic and inelastic collisions. We demonstrate that the presence of a discrete spectrum of excited states due to the process of electron back scattering leads to the appearance of a quasicontinuous flux of energy in the elastic region, similar to the flux created by means of energy loss in elastic impacts. In the absence of channels of energy dissipation connected with energy loss in elastic impacts and in the presence of several excited states, information about the initial EDF injected in a field of arbitrary configuration, can be transmitted over an unlimited distance.The process of the relaxation has the nature of undamped oscillations. The introduction of channels of energy dissipation results in a damped oscillatory relaxation character of the EDF injected into a uniform field and in the establishment of a homogeneous EDF in this field. The relaxation of an EDF injected into a spatially periodic resonance field results in the distribution function having specific maxima which change in energy and coordinates along the resonance paths in accordance with the potential distribution (the so-called bunching effect). This effect can be used for the interpretation of EDF formation in S- and P-striations in inert gas discharges at low pressures and currents.

In this paper plane-wave reflection and transmission phenomena in slabs of uniaxial bi-anisotropic media are theoretically considered. The axis direction is in the interface plane and normal incidence of the plane wave is assumed. Chiral reciprocal slabs and a special class of non-reciprocal media are covered. The study is relevant to recent experimental studies of arrays of parallel spirals. The present theory gives an analytical model of such artificial bi-anisotropic media.

The multi-harmonic reflection from a plane boundary with a nonlinear medium is discussed. The main attention is focused on two special effects, namely nonlinear suppression of the reflection on the fundamental frequency and the total reflection which can occur at several critical angles in a nonlinear case.

In order to investigate the potential of a capillary discharge as a pumping source for soft x-ray lasers the transitions in lithium-like neon were investigated. The discharge with a maximum current of 100 kA through 0.4-0.6 cm diameter gas-filled alumina tubes leads to two fluorescence maxima. The first is due to the collapse of the shock wave, whereas the second, appearing about 60 ns later, is ascribed to the recombination of ions and is enhanced by stimulated emission of radiation. By measuring at different tube lengths, the maximum gain-length product for the 29.2 nm transition was determined to be . A semi-empirical model for the discharge indicates that only part of the current drives a shock wave into the centre, while the other part flows through the surface region of the insulator. This plays an important role insofar as (i) it limits the maximum obtainable plasma temperature and (ii) it supplies sufficient ablated matter for a rapid cooling of the plasma necessary to obtain an inversion in the excited states of the ions. Gain appears after the electron temperature in the centre of the plasma has dropped below about 15 eV. This is reached during the falling edge of the recombination phase.

In the present paper a detailed (but simple from a mathematical point of view) threshold analysis of room-temperature pulse operation of ultraviolet light (UV) emitting GaN/AlGaN/AlN vertical-cavity electrically pumped surface-emitting lasers (VCSELs) is carried out to examine the possible use of this semiconductor injection laser configuration in future mass application. Several VCSEL structures are considered. An index-guided nitride single quantum well (SQW) VCSEL structure ensures the best laser performance, as expected, particularly in the case of small-size devices. But surprisingly, gain-guided SQW VCSELs are found to exhibit comparable thresholds with much simpler double-heterostructure (DH) VCSELs of bulk active regions. Moreover, thresholds of DH nitride VCSELs are proved to be much less sensitive to all optical losses (for example material absorption as well as diffraction, scattering, and end losses) than their SQW counterparts. Therefore the SQW VCSELs need more advanced technology (making possible achievement of lower dislocation densities and/or higher facet reflectivities) to be superior to DH ones.

A coherent anti-Stokes Raman scattering (CARS) set-up has been developed to study the reduction of nitric oxide (NO) by a microwave-generated nitrogen plasma under atmospheric pressure. A frequency-doubled Nd:YAG laser provides two pump beams at nm and excites a dye laser, which is tunable between 588 and 615 nm. Density and temperature profile measurements of in the cylindrical microwave discharge by the common CARS technique deliver an axis temperature of 7000 K at P = 800 W input power. The detection of a minority of NO in under atmospheric pressure by CARS is limited to a concentration of 2500 ppm. By applying polarization-sensitive CARS the detection limit can be scaled down to 200 ppm. This technique is used to examine the reduction of NO in a reaction chamber fed by vibrationally excited and N entering the chamber through a nozzle. Behind the nozzle most of the NO is decomposed. An overall reduction efficiency for NO of 65-85% was found, decreasing with growing NO concentration.

Rayleigh scattering by an infinitely long, circular tube with a helical permittivity dyadic is analysed using an integral equation formalism. When the tube is irradiated by either a TE or a TM polarized plane wave, the scattered field is copolarized. For other types of incident plane waves, the vibration ellipse of the far-zone scattered field can differ from that of the incident plane wave.

In this paper we obtain an analytical solution to the harmonic generation processes in a quasiperiodic optical superlattice. The derived theory was applied to an intergrowth optical superlattice made from a single crystal with laminar domain reversal to realize third-harmonic generation processes. The quasiperiodic structure can provide more reciprocal vectors to compensate for the phase mismatches of the optical parametric processes, which make most of the intense harmonic peaks labelled by the corresponding reciprocal vector indices. The dependence of the harmonic intensity spectrum on structure parameters is presented. Conditions for efficient third-harmonic generation are also discussed in detail.

A physical model of the resistance to local failure of an isotropic elastic-fragile body under the impact of a rigid non-deformable sphere is obtained for impact velocities that are much less than the velocities of sound in the body. The impact is considered to consist of loading and unloading phases. The derived formulae characterize stresses in the body developed during loading and unloading. The loading stresses are characterized by the duration of the loading phase only and similarly the unloading stresses are characterized by the duration of the unloading phase. It was found that, when the impact caused micro-failures of the body, the duration of the unloading phase was much larger than the duration of the loading phase, which is different from the elastic impact phenomenon. On the other hand, the unloading stresses are much smaller than loading stresses. We performed experiments to characterize the strength of concrete by measuring the durations of loading and unloading phases of the impacts on concrete specimens of aluminium and steel spheres. The calculated specimens' strengths matched the results of static loading tests well.

The spatial variation of the rotational temperature of the 0-0 band of the A transition of SiH in radio frequency pure silane discharges is investigated by utilizing a method of improved accuracy for the simulation of the emission spectrum. Furthermore, the variation of the rotational temperature as a function of the pressure at the maximum intensity position of the interelectrode space is examined. The results are used to extract information about the relative variations of the electron energy distribution function and the effective electron density in the interelectrode space. Thus, it is considered that there is a sensitive relation of the observed high rotational temperatures to the mean electron energy, provided that the electron energy distribution function does not change. More specifically, a decrease of the rotational temperature is observed on moving away from the powered electrode sheath region and a similar decrease is also detected with increasing pressure. This behaviour is compared with the spatial emission intensity profiles. The variation of the space-integrated emission intensity under the various discharge conditions, related to the modification of the effective electron density, is also presented.

Properties both of the discharge and of the post-discharge region are studied through the so-called short-lived afterglow generated at 340 Pa by two similar coaxial cavities resonating at 433 and 2450 MHz. Simultaneous Raman Stokes scattering and optical emission spectroscopies are performed. The gas temperature profiles of the various regions are built up through exploitation of and rotationally resolved spectra and by application of an original method involving the densities estimated from the Raman spectra. In the post-discharge region, the latter give the Treanor temperature which is assimilated to the vibrational temperature of in the discharge. The vibrational distribution function of in the short-lived afterglow is compared with the Treanor-Gordiets-like model and found to exhibit a larger excitation at 433 MHz. In this region, the model predicts a marked maximum of the average vibrational energy per molecule at a position where emissions' intensities are also the highest. The correlation of and densities shows that the 2450 MHz frequency has a slightly larger density in our case than it has for the other case. These results are discussed through the comparison of these two plasma sources in terms of production of molecular metastable electronic states and Penning ionization.

This paper describes the low-pressure positive column in electronegative gases taking into account space charge effects. It shows how the plasma joins to the sheath via a transition layer as in electropositive gases, but also demonstrates significant differences in the particle and potential distributions and the scale of the sheath. The treatment is in the main computational, but is related to the analytical sheath approximation and to the plasma approximation. The application of matched asymptotic expansions to the problem is also considered. The analogous situation in two-electron-temperature plasmas is also treated.

A fluid model of magnetically confined surface-wave plasma columns maintained in a diffusion-controlled regime is given. The propagation of the Trivelpiece-Gould mode which sustains the discharge is in a strong magnetic field. The self-consistent wave-discharge behaviour is ensured by a nonlocal nonlinearity involving transport (diffusion) along the external magnetic field. Simultaneous variation along the discharge's length of the plasma density and maintenance field intensity is the final result presenting the axial structure of the discharge.

This paper concerns theoretical and experimental investigations of the effect of a conductor coating on the onset voltage of a corona on overhead transmission-line conductors. The onset voltage for a self-maintained discharge on the basis of discharge physics is evaluated. This calls first for accurate calculation of the electrical field in the vicinity of a coated conductor and its correlation to the field values near a bare conductor of the same radius. The well-known charge simulation technique is used for field calculation. The calculated electrical field values are utilized in evaluating the onset voltage of positive and negative coronas on bare and coated conductors. The onset voltage increases with a conductor coating. The calculated onset-voltage values agreed satisfactorily with those measured for laboratory models and full-scale test lines.

The calculation of the electrical conductivity of thermal plasma has been performed including the contribution of the ionic current, considering molecular ions and using a rather strong F- charge transfer interaction. The comparison between the new values and the previous ones, in the temperature range 1000-5000 K and for pressures in the range 0.1-1.6 MPa, shows that there is an important difference in particular under 2500 K. The increase of F- interaction has a very weak influence on the calculation of the electrical conductivity but the role of the electron-molecule interaction is important at low temperature. New values are given which allow one to complete the database of 's properties.

To investigate the break phenomenon in high-voltage circuit breakers, a novel experimental approach combining spectroscopy and imagery for measuring electron density, temperature and arc geometry is presented. Images of the arc were taken using a narrow band optical filter, and spectra of the entire arc and in the same spectral region were recorded simultaneously. We report tests both on this method and on the available literature data and the results obtained on two different circuit breaker models.

For the high-current phase (I = 2 kA to 10 kA) we chose to study the well isolated 624-641 nm fluorine lines radiating at elevated temperatures, expected to be in the range 15 000-20 000 K. With electronic densities higher than , the Stark effect, as the predominant line broadening mechanism, yields a direct relation between plasma conditions and the measured spectrum. Corrections for eventual self-absorption were applied with the arc geometry deduced from the corresponding images. The results thus obtained compare favourably with and show less scatter than those of the conventional Boltzmann diagram method. They also agree with numerical simulations.

During the extinction phase, copper lines between 510 nm and 522 nm radiating at lower temperatures were selected for similar measurements. The images reveal that either a filament-like arc or well isolated hot gas pockets are present during extinction. The measured temperature was still high even a few hundred microseconds before ultimate extinction. This result is fully compatible with computations of the cooling process. The hot gas pockets could be used as a tracer for flow velocity measurements.

A specially designed thermal plasma reactor system for the investigation of arc-cathode erosion has been set up. By using an OMA-spectrometer system, emission spectroscopic measurements of electron temperature and electron number density in the cathode region have been performed, together with single-colour and two-colour pyrometry of cathode temperature distributions. Observation of cathode spot behaviour has been carried out simultaneously by employing a telemicroscope and a high-speed vision system. Cathodes have been examined by SEM and EDX after arcing. For pure tungsten cathodes, the initial cathode geometry has almost no effect on the cathode spot's behaviour due to the molten state of the cathode spot. The major erosion mechanism is the ejection of liquid droplets from the cathode spot. However, the initial cathode geometry has a certain influence on the cathode's erosion for 2% thoriated tungsten cathodes. A highly non-uniform erosion pattern will occur if the cathode is overcooled, probably due to ion bombardment in the low-temperature regions of the arc-attachment spot.

Time resolved multichannel emission spectroscopy has been applied to study emission in the 200-500 nm spectral range produced by a pulsed positive corona discharge. The discharge was driven in coaxial geometry by an HV power supply (100 kV/1 kA) at atmospheric pressure in nitrogen, and in and mixtures. Emission of NO- (-) and 2.PG (-) bands has been studied in order to trace the development of and electronic states during both discharge and post-discharge periods. Analysis of spectroscopic data indicates an evolution of the electron mean energy during the discharge pulse in the range 20-1 eV and post-discharge kinetics of the NO and electronic states which is predominantly controlled by , v = 0,1) metastable species.

Fourier collocation and Fourier Galerkin methods were employed for numerical solution of phase-transition problems in two dimensions using the phase-field model. These methods were chosen in order to be able to describe naturally the temporal evolution of periodic structures. The applications to a modified Stefan problem and interphase boundary motion driven by mean curvature are discussed. These two particular problems were chosen because their phase-field description has received much attention both from mathematical and from computational points of view. These phase-transition problems were modelled in a two-dimensional periodic cell with no boundary conditions applied explicitly to the governing equations. This procedure allows modelling of more complicated periodic structures than those described here.

Current-voltage measurements are the most widely used technique for testing properties of grading materials. However, surface potential measurements seem to be more representative of these materials' actual behaviour. In order to discuss this issue, a wide range of stress grading materials, loaded with both SiC and ZnO at various fractions, are tested in dc and in 50 Hz ac, both with current-voltage and with surface potential measurements. The latter are compared with simulations performed with analytical and numerical techniques. The three methods are in good agreement. Moreover, on the one hand, simulations show that, when the grading effect is observed, the field that the material withstands is far below the field required for non-linear behaviour. Hence, a nonlinear relationship of the resistivity versus the electrical field does not seem to be necessary for achieving grading optimization. On the other hand, measurements show that all the materials studied here are capacitive at 50 Hz ; they are not suitable for grading purposes at that frequency, although they have a grading behaviour in dc. Since there is no direct link between current-voltage characteristics and surface potential measurements, the latter seem to provide much better insight into grading materials' actual performances.

Faraday-effect measurements have been carried out at room temperature for -containing lithium borate glasses to evaluate the magneto-optical figure of merit in the wavelength range of 350-850 nm. The magneto-optical figure of merit tends to increase with decreasing wavelength except for the range within which absorption bands due to the 4f-4f transitions are observed. Glasses with low content and high concentration of exhibit fairly large magneto-optical figures of merit at around 400 nm which corresponds to the emission wavelength of the (Ga, In)N laser diode; the magneto-optical figure of merit of glass is more than at 400 nm under an external magnetic field of 15 kOe. The analyses of the wavelength dependence of the Verdet constant indicate that the magnitude of the Verdet constant is large because the effective transition probability is high, coincident with the early suggestion by Shafer and Suits [ J. Am. Ceram. Soc. 49 (1966) 261]. This suggests that the magnitude of the Verdet constant remains large even in the wavelength range far from the position of the optical absorption peak due to the 4f-5d transition which causes the Faraday effect. Because the absorbance due to the 4f-5d transition is low in such a wavelength range, the -containing glasses show large magneto-optical figures of merit.

The increase in sensitivity of quartz caused by or irradiation followed by high-temperature activation has been studied further. The model previously suggested, including a reservoir through which holes get into the recombination centre, thus increasing the sensitivity to a given test dose, is now given a concrete mathematical form. Sets of simultaneous differential equations for the various stages of irradiation and heating are written and numerically solved sequentially in order to simulate the physical processes taking place during the experiments. The dependence of the sensitivity on the excitation dose is followed, in particular for the high-dose range in which the sensitivity approaches saturation. A distinction between reservoir and centre saturation is made. The assumption of an exponential approach to saturation is tested, showing that, indeed, even in this complicated situation the exponential approximation is valid. As shown in previous works, using the exponential approximation in cases in which the sensitivity dependence is beyond the linear range helps in evaluating the archaeological doses in the dating of pottery by irradiation of the quartz grains in it. Also the effect of radiation quenching and the attempts to correct for quenching in order to improve the determination of the extrapolated natural dose which leads to the age determination are considered. The effect of the existence of a competing electron trap which appears to be a necessary condition for the occurrence of these effects is also discussed.

Thermoluminescence glow-curve deconvolution (GCD) functions are proposed for first, second and general orders of kinetics. The free parameters of the GCD functions are the maximum peak intensity and the maximum peak temperature , which can be obtained experimentally. The activation energy (E) and the order of kinetics (b) in the case of general order kinetics are the additional free parameters.

We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of in tumour cells after injection of a boron compound (in our case , or BSH). With the Mephisto (microscope à emission de photoélectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy.

It is shown that the acoustic waves generated during laser ablation can be used to determine the ablation threshold and the ablation rate for different fluences and depths and also to characterize the different regions of the process. On-line measurement of the individual ablation rate is possible by observation of the delay of the arrival of the acoustic wave to a piezoelectric detector located behind the sample.