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The non - accelerator observation of the long - range strong nuclear interaction is presented. We have studied the low - temperature spectra (reflection and luminescence) of the LiH (without strong interaction in hydrogen nucleus) and LiD (with strong interaction in deuterium nucleus) crystals which are different by term of one neutron from each other. The experimental observation of isotopic shift (103 meV) of the phononless free excitons emission line in LiD crystals is a direct manifestation of the long - range strong nuclear interaction. Such conclusion is made to the fact that the gravitation, electromagnetic and weak interactions are the same in both kind crystals, it only emerges the strong interaction in deuterium nucleus. As far as Born - Oppenheimer approximation does not work in isotope effect, we tentative connect our experimental observation with long - range hadron - lepton interaction. Most important study of the LiHx D1-x mixed crystals is the first measurement of the long - range force dependence of strong nuclear interaction on the distance between nucleons in deuterium nucleus

The experimental evidence of renormalization the energy of the elementary excitations in solids which are differ by term of one neutron from each other by the strong (nuclear) interaction has been presented for the first time. This evidence is based on two independent results: 1) The increase exciton energy on 103 meV is caused by the adding of one neutron (using LiD crystals instead LiH ones); 2) After increasing the amounts by one neutron the energy of LO phonons has decreased by 36 meV. The last one is directly seen from luminescence and scattering spectra. As far as the gravitation, electromagnetic and weak interactions are the same in both of kind crystals, it only changes the strong interaction. Therefore a logical conclusion is made that the renormalization of the energy of electromagnetic excitations (excitons, phonons) is carried out by the strong (nuclear) interaction.

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. The magnetic resonance in FeNi/Bi/FeNi trilayer films with nonmagnetic semimetal spacer has been experimentally studied. It is found that the microwave absorption spectrum of samples has a complicated shape dependent on the nonmagnetic spacer thickness. In the interval of Bi layer thicknesses within 3–15 nm, the interlayer coupling has an antiferromagnetic character. © 2015, Pleiades Publishing, Ltd.

Most of the physical properties of a solid depend on its isotopic composition in some way or another. Scientific interest, technological promise and increased availability of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled crystals. A great number of stable isotopes and well-developed methods for their separation have made it possible to grow crystals of C, LiH, ZnO, ZnSe, CuCl, GaN, GaAs, CdS, Cu2O, Si, Ge and α-Sn with a controllable isotopic composition. Among these compounds, LiH possesses the largest value of the isotope effect. The great number of theoretical and experimental data suggest that the isotopic composition of a crystal lattice exerts some influence on the vibrational properties of crystals. These effects are fairly large and can be readily measured by modern experimental techniques (ultrasound, Brillouin and Raman scattering and neutron scattering). In addition, crystals of different isotopic compositions possess different Debye temperatures. This difference between an LiH crystal and its deuterated analogue exceeds a 100 K. Very pronounced and general effects of isotopic substitution are observed in phonon spectra. The scattering lines in isotopically mixed crystals are not only shifted (the shift of LO lines exceeds 100 cm−1) but are also broadened. This broadening is related to the isotopic disorder of the crystal lattice. It is shown that the degree of a change in the scattering potential is different for different isotopic mixed crystals. In the case of germanium and diamond crystals, phonon scattering is weak, which allows one to apply successfully the coherent potential approximation (CPA) for describing the shift and broadening of scattering lines. In the case of lithium hydride, the change in the scattering potential is so strong that it results in phonon localization, which is directly observed in experiments. The common nature of the isotopic and disorder effects in a wide range of crystals is emphasized. Copyright © 2001 John Wiley & Sons, Ltd.

Most of the physical properties of a solid depend to a greater or lesser degree on its isotopic composition. Scientific interest, technological promise and increased availability of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor and insulator crystals. A systematic analysis is for the first time presented of isotopic and disorder effects observed in crystals of various isotopic composition via low-temperature large-radius exciton spectroscopy. Substituting a light isotope with a heavy one increases the interband transition energy and the binding energy of the Wannier-Mott exciton as well as the magnitude of the longitudinal-transverse splitting. The nonlinear variation of these quantities with the isotope concentration is due to the isotopic disordering of the crystal lattice and is consistent with the concentration dependence of line half-widths in exciton reflection and luminescence spectra. The common nature of the isotopic and disorder effects in the crystals of C, LiH, ZnO, ZnSe, CuCl, CdS, , GaAs, Si and Ge is emphasized. The review closes with an outlook on the exciting future possibilities offered through isotope control of a wide range of semiconductor and insulator crystals.

The results of the quantitative investigations of the renormalization of the absorption edge of different compounds by the isotope effect are described., 7 pages, 3 figures

Data are provided for an experimental study of the dependence of sintering temperature on heating time and rate, grain size composition, and on the frequency of the current supplied, obtained when producing metal powder articles by induction sintering with a high-frequency current. It is shown that with the help of a computer it is possible to determine which of the equations suggested describes the sintering rate for particles by this method.

The effect of disorder on exciton binding energy on the mirror reflection exciton spectra of ${\mathrm{LiH}}_{\mathit{x}}$${\mathrm{D}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ (0x1) mixed crystals has been shown. The short-range character of the potential of a disordered crystal lattice with isotope substitution is responsible for the broadening of the valence and conduction bands. The last one causes the reduced exciton binding energy relative to the virtual crystal modeling value in the vicinity of the middle meaning concentration. The detailed comparison of the experimental results on the concentration's dependence of the exciton Rydberg value with the calculations in the frame of the Wannier-Mott exciton model in disordered media has shown a good agreement. \textcopyright{} 1996 The American Physical Society.

The results of the long term investigation (see, e.g. review [1] ) of the wide gap insulating crystals optical spectra have shown that their fundamental absorption edge is formed by the exciton states with a large oscillator strength. On the other hand, it is well-known that just the excitons play the important role in the manifestation of the nonlinear properties in the optical spectra of the huge number of the nonmetallic compounds. Particularly, on the example of the ionic semiconductors it was shown (see, e.g. reviews [2; 3]) that the excitons appoint the main channel of electronic transitions in the stimulated emission. Namely this circumstance provides the high energetical yield of the coherent emission per unit volume of the matter.

The development of the microwave technique of the MSW basis stimulated the interest to the investigation on the effects, appearing under interaction between MSW and other types of waves, which propagate in magnetic dielectric films, including optic ones. In this case the use of magnetostatic waves gives us the possibility of both the modulation of light and of carrying out a special analysis of microwave signals: an instant spectrum Fourier analysis, disappearing and so on.

The results of a quantitative study of the renormalization of the binding energy of the Wannier–Mott exciton by the isotope effect are presented for the first time. For this purpose, accurate measurements of the intrinsic luminescence and mirror reflection spectra of LiHxD1−x mixed crystals with a clean surface in the temperature range 2–100 K were carried out. The nonlinear dependence of exciton binding energy Eb on the isotope mass Eb~f(x) is caused by the fluctuation broadening of the bands, which is connected with the isotope-induced disorder. The temperature dependence of the exciton binding energy is briefly discussed. The extrapolation of the asymptotic linear behaviour of the exciton maximum energy to T = 0 K enables us to estimate the zero-point renormalization of the exciton binding energy.

An experimental study is made of resonant secondary emission, reflection, and excitation spectra which indicate the existence of bound excitons in LiHMg crystals. The spectroscopic properties of the bound exciton are studied by selectively excited luminescence and resonant Raman scattering. The resonance energy of the bound exciton is estimated to be 4.842 eV. For the first time, the transformation of resonant Raman scattering into luminescence is found when the incident photon energy is above the resonance. [Russian Text Ignored.]

The results of theoretical and experimental study of vibrational relaxation processes in impurity centres with a strong electron-phonon interaction are presented. General expressions are obtained which describe the temporal evolution of the configurational-coordinate distribution function and the envelope of the emission spectrum consisting of ordinary and hot luminescence. The problem is solved exactly in the harmonic approximation with allowance made for both linear and quadratic vibronic coupling providing a small number of actual configurational coordinates. The hot luminescence bands in KI-Tl positioned at 3.1 and 2.25 eV are detected. The computations show that in Tl+ centres the main portion of the excess vibrational energy relaxes in a time shorter than the mean period of vibrations ( approximately=0.5 ps) and, therefore, the observed spectral features are caused by the first classical turning point in the configurational-coordinate relaxation law. Thus, the centres under study serve as an example of ultrafast relaxing systems. Other weak spectral features are related with the complicated structure of adiabatic potential surfaces in the excited state and are interpreted as a barrier and post-tunnel hot luminescence.

The coexistence of free and self-trapped excitons, the problem of the activation barrier for self-trapping, and the peculiarities of luminescence of hot and thermalizedexcitons in various ionic crystals are discussed.

The hot luminescence of self-trapping excitons is discovered in NaI and KI single crystals. The temperature behaviour of hot emission spectra in the range of 4.2 to 170 K and the corresponding excitation spectra are studied. Basing on the theory of resonant secondary emission developed recently a description of the observed luminescence in terms of the relaxation of a configurational coordinate is given. The calculations of local lattice dynamics of a self-trapped exciton determining its relaxation law and the shape of the hot emission spectra are presented. A comparison of the theory with the experiment provides a detailed picture of the exciton relaxation into the self-trapped state. [Russian Text Ignored].

For ionic crystals with a wide energy gap an intrinsic luminescence in the edge region of fundamental absorption has been discovered. The edge luminescence of NaI (5.55 eV), MgO (7.6–7.7 eV) and MgWO 4 (5.8 eV) arises mainly in the course of the annihilation of mobile excitons. In alkali halides and tungstates the edge emission appears together with the emission of self-trapped excitons, whereas the process of self-trapping requires some activation energy.

The luminescence and excitation spectra of free and self-trapped excitons, whose states are separated by a small potential barrier, are investigated experimentally on an example of NaI and RbI crystals. The height of the self-trapping barrier is established to be independent of the kinetic energy of an exciton, but it is inversely proportional to its first quantum number. The spectroscopic manifestation of the self-trapping barrier in the excitation spectra of the steady-state luminescence of self-trapped excitons is shown. The value of barrier height obtained experimentally coincides best of all with the value calculated from the theoretical model of the polarizing exciton. The evolution of the luminescence excitation spectra of self-trapped excitons in a temperature interval 4.2 to 80 K is studied. If the relaxation mechanism of free excitons is reflected in the oscillating structure (the oscillation period is equal to the energy of LO phonon) of luminescence excitation spectra, then the further exciton relaxation along the adiabatic sheet is manifested most directly in the structure of hot luminescence spectra of the self-trapping excitons. [Russion Text Ignored]

The multiphonon resonant Raman scattering spectra in NaI and LiH (LiD) cubic crystals characterized by self-trapping of excitons are investigated experimentally. The first-order scattering cross section is established to depend on the wave vector. The frequency dispersion of the secondorder scattering cross section is in agreement with the theory. The 1S and 2S excitons as intermediate states as well as the damping of excitons are taken into account. The temperature dependence of the second-order intensity in both luminescence and resonant Raman scattering is studied in the region of 2 to 300 K. This dependence is shown to weaken with the shifting of the exciting light frequency from the exciton band bottom towards the red. The temperature behaviour of the frequency dispersion of the second-order Raman cross section at the temperature change in the crystals with self-trapping excitons is discussed. [Russian Text Ignored].

The results of an experimental and theoretical study of the resonant secondary emission spectra at 4.2 K of wide gap ionic insulators (lattice of the NaCl type) are presented. The well developed character of the free exciton luminescence and the multiphonon resonant Raman scattering spectra (which contain mainly LO lines) point to Frolich intraband scattering of free excitons (polaritons) on LO phonons. It is established that the ratio of the scattered line intensities of the first and second order has a square dependence on the scattered polariton wave vector. For the spectral range 4.97–3.30 eV the dispersion of the scattering cross-section with participation of LO(Γ) phonous has been measured for the first time. A resonant enhancement of the multiphonon scattering line intensities on the LO(Γ), LO(X) and TO(Γ) phonons has been observed. Calculation of the dispersion of the scattering cross-section has been performed using a theoretical model taking into account the scattering of hydrogen-like excitons on LO phonons. Analysis of the cross-section leads to the conclusion that in the excitation frequency range ω > Eg-4R the main contribution to σ(ω) comes from the discrete excitonic states, but for ω Eg-4R the states of the electron-hole continuum play the main role. Agreement between theory and experiment has been achieved by taking into account the electronic damping. The influence of the excitation intensity on the structure of resonant Raman scattering spectra in LiH crystals is also discussed.

Comparative investigations of the mass spectra of eEH2, Me2EH, Et2EH(E = N, P); Me3E, Et3E(E = N, P, As, Sb, Bi). (n-Pr)3E(E = Sb, Bi); (n-Bu)3E(E = P, As); (n-C5H11)3As and (n-C6H13)3As as well as Et2AsBr have been carried out. Deuteroanalogues, metastable transitions and low voltage spectra were used for elucidation of the fragmentation paths. The mass spectra of MeN(CH2)2 and CD3N(CH2)2 were studied to analyse the structure of the fragments. The main degradation path of amines, i.e. α-cleavage, was shown to be untypical for P, As, Sb and Bi derivatives.

Distinct differences are observed on comparison of the fragmentation of tertiary amides (I to XI), and acylphosphines (XII to XVII) and (XX to XXII) under electron-impact, as well as of their vinylogues (XXIII to XXXI) and (XXXIV to XXXV).

The mass spectra of azetidine, 2-methylazetidine, 2-phenylazetidine, methylene-bis-azetidines, their N-halo- and N-tosyl derivatives, 2-phenylazetine as well as N,N-dimethylmethane sulphonamide, N,N-dimethyl and N,N-diethyl- p-toluene sulphonamides have been investigated. The fragmentation of azetidine derivatives via the open form of the molecular ion is discussed.

Luminescent emission greater than the band edge of PbI 2 is investigated. It is proposed that the emission is from metastable excitons, possibly from hyperbolic excitons.