The hierarchical trees have been constructed for the AX3 crystal family, significant steps of this construction being explained in detail. It has made possible to establish the archetypes of the crystal structures that are high-symmetry approximations for subfamilies of the crystals under consideration.

The temperature dependence of exciton-polariton damping in InP bulk crystal was extracted by the method of integrated absorption. The extraction procedure excluding the contribution of inhomogeneous broadening into the exciton ground state absorption linewidth is graphically illustrated. The extracted temperature-dependent damping is analyzed regarding the primary dissipative mechanism in order to determine the material parameters of exciton-polariton scattering by acoustic and optical phonons.

The results of experimental studies of a compact high-voltage pulse generator are presented. The generator is based on two artificial double forming lines in a collapsed circuit, which are switched by gas spark gaps; it also contains a peaking gas spark gap, transmission lines filled with a liquid dielectric, and a load equivalent. The characteristics of this generator were studied in the charging-voltage range of up to 100 kV. When the voltage pulse duration from the forming line was 100 ns, current pulses with an amplitude of 18 kA and a rise time of ~18 ns were obtained across an ohmic load.

Abstract This paper highlights the temperature factor in the experimental study of total absorption as a method for experimental validation and the study of the exciton–polariton light transfer mechanism near the fundamental absorption edge in semiconductor crystals with spatial dispersion. The results of experimental studies of temperature-dependent total exciton absorption are generalized. The experimentally determined critical temperatures above which total absorption becomes constant, the corresponding critical damping parameter, and longitudinal–transverse splittings for the studied semiconductors CdTe, GaAs, InP, ZnSe, and ZnTe are presented.

This paper highlights the temperature factor in the experimental study of total absorption as a method for experimental validation and the study of the exciton–polariton light transfer mechanism near the fundamental absorption edge in semiconductor crystals with spatial dispersion. The results of experimental studies of temperature-dependent total exciton absorption are generalized. The experimentally determined critical temperatures above which total absorption becomes constant, the corresponding critical damping parameter, and longitudinal–transverse splittings for the studied semiconductors CdTe, GaAs, InP, ZnSe, and ZnTe are presented.

The transformation of excitonic states in the raising magnetic field has been investigated beginning with the diamagnetic exciton (strong field) through excitonic magnetopolymer (superstrong field) to the QEL exciton (hyperstrong magnetic field). The effects induced by this transformation were considered. The capability of the exciton as a model object to study the hydrogen and positron atoms in superstrong and hyperstrong magnetic fields was also analysed.

Magnetotransmission (MT) at magnetic fields up to 29 T was used to study the electronic structure of $\mathrm{CuInS}{\mathrm{e}}_{2}$ in thin polycrystalline films. The zero field absorption spectra exhibited resolved A, B, and C free excitons. Quantum oscillations, due to diamagnetic excitons comprising electrons and holes from Landau levels quantized in the conduction and valence band, respectively, appeared in the MT spectra at fields over 5 T. Spectral energies of Landau levels and binding energies of the corresponding diamagnetic excitons, theoretically calculated assuming a quasicubic approximation of the $\mathrm{CuInS}{\mathrm{e}}_{2}$ tetragonal lattice structure, helped to identify the character of the experimentally observed diamagnetic excitons. Spectral energies of diamagnetic excitons in the MT spectra with different circular polarizations were used to determine the electron and light hole effective masses, whereas heavy hole masses as well as the \ensuremath{\gamma} and ${\ensuremath{\gamma}}_{1}$ Luttinger parameters, ${E}_{p}$ Kane energy, and F parameter of the influence of remote bands, as well as their polaron values, were calculated using the Luttinger theory.

Electrical characteristics of low-inductance capillary-type discharge have been determined by numerical model calculations, which ensure high efficiency of energy supply to a plasma column with an aspect ratio of 1: 100. The EUV argon laser based on this discharge provides a gain of g + > 1 cm–1 on the operating transition and ensures single-pass spontaneous lasing with g + l > 25 (where l is the active medium length).

На основании результатов расчетов определены электрофизические характеристики капиллярного разряда, обеспечивающие при аспектном отношении диаметра и длины плазменного сгустка 1 : 100 и высокой эффективности ввода энергии в плазму получение коэффициента усиления g+>1 cm-1 на рабочем переходе и генерацию в однопроходном режиме усиления спонтанного излучения с g+l>25 (l --- длина активной среды).

The present paper summarizes the results of studying of  nanosecond low-inductive extended z‑discharge as source of electromagnetic  radiations and analyzes the works of other research groups that can throw upon additional light and hereunder promote to best understanding of physics of the phenomena and processes observed in authors' researches. The analysis is of main interest towards development of compact electrodischarge sources of coherent and low-coherent radiation including X-ray range.

Modifications of the exciton structure of the fundamental absorption edge in the GaAs crystals is experimentally studied at T = 1.7 K using the optical pumping at a photon energy that is significantly greater than the band gap. An increase in the amplitude of the fundamental state of the exciton is observed at a stable maximum energy. The dependence of the integral absorption on the pump intensity is interpreted in the framework of the concept of the excitonic polariton using the dissipative scattering of the exciton by free electrons that are generated by the pumping radiation. The constant of the electron-exciton interaction can be estimated with the aid of the solution to the inverse problem for initial pump levels. The integral absorption of the fundamental exciton state at liquid-helium temperatures can be used to characterize the purity of an epitaxial layer. The reasons for the lower saturation level of the integral absorption that is significantly less than the calculated level determined by the exciton oscillator strength need to be further studied.

The temperature dependence of the fundamental absorption edge in free-standing “epitaxial” InP layers has been experimentally studied. The integral exciton absorption coefficient K(T) exhibits an increase at low temperatures, which is explained in terms of the exciton-polariton mechanism of light transfer in semi-conductor crystals with spatial dispersion. A critical temperature (T c = 200 K), above which the integral absorption becomes constant, has been experimentally determined, and the corresponding critical decay parameter (Γc = 0.341 meV), longitudinal-transverse splitting (ħωLT = 0.175 meV), and oscillator strength of the exciton transition (β = 0.237 × 10−4) have been calculated. The temperature dependence of the true dissipative decay has been determined.

Temperature variations in the fundamental absorption edge of long-period In x Ga 1 − x As/GaAs structures are studied for samples with different numbers of quantum wells and similar periods. The quantum wells were close in composition and width. Experimental data are interpreted in the model of exciton-polariton light transfer involving localized excitons in confined structures with a finite number of quantum wells. The experimentally observed low-temperature anomaly of the integrated absorption coefficient is attributed to reemission of resonance localized excitons along a finite chain of quantum wells, with no excitonic transfer. The radiative decay time of an exciton in a single quantum well is estimated from the experimental data. It is demonstrated that, at low temperatures, the major contribution to the width of the experimentally observed absorption line corresponding to the ground heavy-hole exciton state is made by inhomogeneous broadening of the line by the field of potential fluctuations associated with the compositional disorder of the alloy. At low temperatures, the inhomogeneous broadening is much more pronounced than the broadening governed by the true radiative and nonradiative dissipative decay.

Temperature variations in the fundamental absorption edge of longperiod In xGa 1- xAs/GaAs structures are studied for samples with different numbers of quantum wells and similar periods. The quantum wells were close in composition and width. Experimental data are interpreted in the model of exciton-polari� ton light transfer involving localized excitons in confined structures with a finite number of quantum wells. The experimentally observed lowtemperature anomaly of the integrated absorption coefficient is attributed to reemission of resonance localized excitons along a finite chain of quantum wells, with no excitonic transfer. The radiative decay time of an exciton in a single quantum well is estimated from the experimental data. It is demonstrated that, at low temperatures, the major contribution to the width of the experimentally observed absorption line corresponding to the ground heavyhole exciton state is made by inhomogeneous broadening of the line by the field of potential fluctuations associated with the compositional disorder of the alloy. At low temperatures, the inhomogeneous broadening is much more pronounced than the broadening governed by the true radiative and nonradiative dissipative decay.

The absorption edge spectra and excitonic absorption index integrated over frequency were measured for semiconductor solid solutions AlxGa1–xAs with large concentrations of substituting Al (x = 0.15 and 0.21). For the ground-state exciton the temperature dependence of integral absorption was established to possess features characteristic of exciton-polaritons in a quasi-homogeneous semiconductor with spatial dispersion. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The absorption-edge spectra have been studied in the temperature range from 4 to 300 K for single-crystal CdTe, ZnTe, GaAs wafers and GaAs/(Al,Ga)As multiple quantum well (MQW) structures. In all cases the frequency integrated absorption coefficient K is found to increase monotonously with temperature T up to T equals T* and to keep constant above T*. The temperatures T*, depending on semiconducting materials, might be considered as critical ones corresponding to a change in polaritonic energy transport mechanism due to the lack of spatial dispersion at T > T*. It was shown, that though the measured temperature T* approximately 102 K correspond to much larger linewidths than could be explained by using the theoretical value of the exciton damping parameter, this discrepancy can be overcome if a temperature-dependent inhomogeneous broadening is taken into account consistently. A similar temperature dependence of K with T* approximately equals 20 K has been observed for the first time in GaAs/(Al,Ga)As MQW-structures.

The absorption-edge spectra have been studied in the temperature range from 4 to 300 K for single-crystal CdTe, ZnTe, GaAs wafers and GaAs/(Al,Ga)As multiple quantum well (MQW) structures. In all cases the frequency integrated absorption coefficient K is found to increase monotonously with temperature T up to T = T* and to keep constant above T*. The temperatures T*, depending on semiconducting materials, might be considered as critical ones corresponding to a change in polaritonic ener~ transport mechanism due to the lack of spatial dispersion at T<T*. It was shown, that though the measured temperatures T -. o2 K correspond to much larger linewidths than could be explained by using the theoretical value of the exciton damping parameter, this discrepancy can be overcome if a temperature-dependent inhomogeneous broadening is taken into account consistently. A similar temperature dependence of K with T* = 20 K has been observed for the first time in GaAs/( Al, Ga)As MQW-structures.

A comparative study of the temperature dependence of the absorption edge has been performed with thin single-crystal wafers of bulk GaAs and multilayer quantum-size GaAs/Ga0.3Al0.7As structures with the well and barrier thicknesses La=Lb approximately=135 Å in the temperature range T=4-300 K. The total number of periods was N>20. The authors consider the quantity K*, which is proportional to the integral absorption coefficient calculated as a product of the line halfwidth and the optical density at the exciton band maximum. In bulk samples K* shows a sharp increase by nearly an order of magnitude, up to T* approximately= 110 K, and then remains roughly constant. The temperature T* may be considered as critical for the excitonic polariton-mechanical exciton transition. A similar behaviour of K* was observed for superlattices with a slightly increasing integral absorption up to a temperature of T* approximately=20 K. This fact is considered as evidence for the polariton nature of light absorption at T