Analysis op mean statistical spectral dependences of coefficients of aerosol absorption in the range 0.59–10 μm

A comparison of the mean statistical coefficients of aerosol absorption in the transparency windows of the atmosphere, obtained by the authors, with the results of the corresponding measurements known from published sources indicates the feasibility of obtaining data for optical weather prognosis at different geographical locations.Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 10, pp. 103–106, October, 1972.     

The fundamental absorption band of amorphous germanium

The index of attenuationk() of evaporated films of amorphous Ge was measured in the spectral range of 1.95 to 5.3 eV by measuring the transmissivity of samples with thicknesses varying from 560 to 1510 Å. It is shown that in comparison with crystalline Ge the absorption is significantly shifted towards lower energies and the peak at 4·5 eV is absent. Using these data and the data onk() determined in other spectral ranges up to 25 eV by various authors, the index of refractionn() was calculated by Kramers-Kronig analysis. The absorption of amorphous Ge is compared with that of crystalline Ge and the differences are discussed.The authors thank Mr. Z. Balej for the preparation of the thin films used in our measurements, Dr. J. Nadrchal for help with the calculations, Dr. T. M. Donovan for the information on his measurements of photoemission before its publication and Prof. R. Grigprovici for helpful discussions.     

Absorption of external thermal radiation in asymmetrically illuminated droplets

A theoretical model of thermal radiation absorption in semi-transparent droplets at the surface and inside a fuel spray is presented. Asymmetry of droplet illumination is taken into account. Results of Mie calculations of thermal radiation absorption inside large spherical droplets illuminated from a hemisphere are presented. Simple approximations for the angular and radial dependencies of the absorbed radiation power are suggested. These approximations are generalisations of the approximations suggested earlier by the authors for the case of symmetric illumination of droplets. They predict the results close to those which follow from the Mie calculations. Results of approximate calculations for a typical diesel fuel droplet at the periphery of the spray are presented. As in the case of symmetrical droplet illumination, an increased absorption of thermal radiation in the central area of the droplet is predicted. Also, at the illuminated side of the droplet, the absorption of radiation in a thin layer near the surface of the droplet is predicted, as in the case of symmetrical droplet illumination. Absorption of radiation in the central area of the droplet is related to the contribution of radiation in the spectral ranges of semi-transparency. The maximum of radiation absorption near the droplet surface is linked to the contribution of radiation in the vicinity of the diesel fuel absorption peak .     

The infrared absorption spectrum of γ-phenylpyridine

The infrared absorption spectrum of-phenylpyridine has been recorded experimentally in the range 600–2000 cm^–1 and the fundamental frequencies and forms of the normal vibrations have been calculated using the valence force field. The experimental and calculated data show satisfactory agreement.In conclusion the authors wish to thank L. A. Gribov for assistance and discussion of the results.     

Some photoelectric and electrical properties of copper-doped gallium arsenide

A study has been made of the conditions for the formation of impurity centers having an ionization energy E _v + 0.1 eV in copper-doped gallium arsenide. Photoconductivity is demonstrated at 10.6 . The results of the photoconductivity study are used to calculate the absorption coefficient and cross section for photon capture by these impurity centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 40–44, September, 1970.The authors thank V. N. Detinko, A. S. Petrov, and A. P. Vyatkin for constant interest in this study.     

Determination of the vertical humidity profile from terrestrial thermal-radar measurements of atmospheric absorption

Results are presented of the restoration of vertical humidity profiles from terrestrial thermal-radar measurements of atmospheric absorption above the continent and the ocean at a series of wavelengths near the rotational resonance of H₂O molecules centered to =1.35 cm. The restoration of the humidity profiles in this work was accomplished by the method of statistical regularization. The effect of additional physical information and various a priori data on the accuracy of the solution of the problem is discussed. The prospects of restoring a broad class of humidity profiles according to radiometric data are noted.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 4, pp. 510–516, April, 1972.The authors are indebted to M. S. Malkevich and A. S. Gurvich for their constant interest in the work and discussion of the results obtained, and likewise to I. A. Gorchakova for the matrix which he kindly provided for our work.     

Examples of optimal orthogonal systems of functions for the microwave absorption coefficient and refractive index

Systems of orthogonal vectors are determined, providing an optimal (in the statistical sense) approximation of the vertical distributions of the molecular absorption coefficient at characteristic microwave wavelengths associated with atmospheric windows and the absorption resonances of O₂ and H₂O, as well as the distribution of the refractive index of the atmosphere in the range 1 mm. Certain properties of the orthogonal vectors are analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 12, pp. 1742–1749, December, 1978.The authors are indebted to M. B. Zinicheva for running the computer calculations of the correlation matrices.     

Some differences in the exponential tail behaviour of the fundamental absorption edge in amorphous and crystalline materials

Some characteristics of optical absorption in the fundamental absorption tail are studied using the parameter which describes the shape of the optical absorption edge of crystalline and amorphous materials. It follows from the experimental data that depends on the morphological state of material. Further, very pronounced linear temperature dependence of was found for crystalline materials whereas only a weak dependence was found for amorphous materials. A unique point of intersection has been observed for all the=f(T) lines pertinent to various crystalline materials in unpolarized light.Lumumbova 1, Praha 8, Czechoslovakia.The author thanks Dr. A. Vako for his attention paid to this work.     

A spectroscopic investigation of the conformational equilibrium of methyl cyclohexane

The vibrational spectra of the axial and equatorial conformations of methyl cyclohexane were computed. The temperature variation of the relative intensity of the 607 (axial) and 547 (equatorial) cm^–1 IR absorption bands were were used to determine H for the liquid and vapor. The IR spectrum at the liquid-vapor transition was investigated.In conclusion, the authors express their sincere gratitude to Z. I. Kaganov for his assistance in the computations and to V. T. Alekxanyan for his useful comments.     

Absorption of intense radiation in a transparent dielectric containing impurities

The dynamics of the process of heating a transparent dielectric medium surrounding a strongly absorbing microimpurity in an intense radiation flux are theoretically considered. It is shown that the size of the region of nonlinear absorption in the dielectric near the microimpurity increases with time no more rapidly than t. A formula is obtained for determination of the threshold intensity which satisfies the criterion of destruction of the surface layer of a solid dielectric.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 90–95, June, 1978.In conclusion, the authors express their thanks to A. M. Bonch-Bruevich for his evaluation of the results obtained.     

Efficiency of the microwave energy absorption in a plasma at high magnetic fields

It was shown experimentally that the efficiency of the microwave energy absorption in an inhomogeneous magnetoactive plasma strongly depends on the polarization of electromagnetic waves entering the plasma. At high magnetic fields satisfying the condition _ce />1 the RHCP wave (right-hand circularly polarized wave) is absorbed most effectively; here _ce and are the electron cyclotron frequency and the angular frequency of an electromagnetic wave respectively. The experimental results are in a good qualitative agreement with theory.On leave fromA. F. Ioffe Physico-Technical Institute, Acad. Sci. USSR, Leningrad. The authors wish to express their appreciation to Drs. V. I.Fedorov and A. D.Pilija from A. F. Ioffe Physico-Technical Institute, Leningrad, for many valuable discussions.     

Influence of induced processes on the spin dynamics of an electron moving in a plane wave

Electron-spin behavior during stimulated radiation and absorption in a plane wave field is analyzed in this paper. It is shown that even when there is no preferred spin orientation on the whole as t, a preferred orientation exists at some finite time. The greatest possible degree of preferred orientation and the time at which it is achieved are found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 65–70, October, 1982.The authors are quite grateful to Prof. I. M. Ternov for constant interest in the research and to Prof. Yu. M. Loskutov for stimulating discussions.     

Effect of the polarization of the electromagnetic wave on wave energy absorption caused by the linear transformation of waves

The paper deals with the experimental verification of the effect of the polarization of the electromagnetic wave on the linear transformation of waves in an inhomogeneous magnetoactive plasma. Experiments were carried out in magnetic field satisfying condition _ce/>1, where _ce, are the electron cyclotron frequency and the frequency of the electromagnetic wave. The expressive dependence of the electromagnetic wave energy absorption on its polarization found experimentally is in excellent agreement with the theory.The authors wish to thank the director of the Institute of Plasma Physics Dr. J. Váa for his interest in this work and to Drs. R. Klíma, V. Kopecký and J. atlov for many valuable discussions and comments.     

A Theoretical Description of the Photodissociation Spectrum of the H2O...HCl Complex

The effect of association of the water molecule and hydrogen chloride on the UV absorption bands is studied. Complete ab initio calculations for the H₂O...HCl complex in the S ₁ and S ₂ states are performed. A mathematical model using Airy functions is developed to describe the absorption cross-sections in a continuous spectrum. The form of the potential is determined by accurate ab initio calculations. The cross-sections of potential surfaces of lower electron states are found from ab initio calculations using the Hartree–Fock, configurational interaction, and multi-configurational interaction techniques. A complete vibrational analysis and an analysis of the change in the electron density for the S ₀ S ₁ transition on moving along the reaction coordinate allow a conclusion to be made on the feasibility of applying the model proposed to the H₂O...HCl complex. The results obtained in the framework of the model using Airy functions show reasonably good agreement with the experiment. For the H₂O...HCl heterodimer, the absorption band has the same structureless form as for the water monomer. The absorption band (peaking at 161 nm) is seen to shift towards short wavelengths as compared with the water monomer H₂O ( 167 nm).     

Low-temperature absorption centers in some simple glasses

At the temperature of liquid nitrogen, glasses were irradiated with Co⁶⁰ radiation and the induced absorption spectra were measured. A strong increase in the 640 nm band was observed in sodium silicate and unleached sodium borosilicate glasses; a new band at 820 nm appeared in potassium silicate glass; and the intensity of the band at 240 nm increased in sodium borate glass and in unleached sodium borosilicate glasses.In conclusion, the authors express their gratitude to N. Z. Andreeva for her assistance in the measurements.     

Resonance absorption of gamma-quanta in one- and two-dimensional crystals

The resonance absorption of gamma-quanta in undisturbed one- and two-dimensional crystals is studied, the form of the resonance lines is determined and the question of the possibility of the existence of the Mössbauer effect in such models is studied. It is found that for one-dimensional crystals the Mössbauer effect is zero with the exception of the case of the perpendicular incidence of gamma-rays on the linear chain and for two-dimensional crystals this effect would be possible in addition only at absolute zero temperature.The authors would like to thank Dr. . Muziká for suggesting the work and for many discussions.     

Nonlinear level crossing in the infrared transitions of optically pumped far infrared laser media

In conjunction with the Stark field induced power enhancement in optically pumped far infrared lasers, absorption transitions in a degenerate two level system under the influence of an weak static Stark field have been analyed. A third order theory to the density matrix formalism leads to zero field level crossing signals for absorption in rate equation approximation and in Doppler limit. For fast relaxation among Zeeman sublevels, the zero field level crossing signal arises from population effect. Optoacoustic measurements have been carried out on the ₅,^qQ(16,8) absorption line of CH₃OH which produces the familiar 119-m laser with the CO₂ 9P(36) pump line. The optoacoustic absorption signals observed are well reproduced by the theoretical expression.     

A two-component interpretation of the far infrared dielectric loss in liquid methyl chloroform

A possible interpretation of the so-called Poley absorption in polar liquids is that it is due to overlapping contributions from liquid- lattice bands together with a contribution from an inertially rolled-off Debye absorption. We propose a test involving the inertially similar but electrically very different molecules methyl chloroform and carbon tetrachloride. This test gives results which offer plausible support for the two-component interpretation.     

On the role of water in some optical properties of alumino-phosphate glasses containing manganese

Optical absorption in broad frequency range (150–5×10⁴ nm) and thermoluminiscence (TL) of the manganese doped alumino-phosphate glasses with two modifiers (Mg, Sr) were measured. It was found that with prolonged melting time the absorption bands at 3·1 m, 5·3 and 5·9 m decrease, new band at 4·2 m appears and that one in UV at about 235 nm increases. Simultaneously the solubility of the glasses in water increases. At longer melted and irradiated glasses the band of electron centres at 210 nm increases while that one of hole centres at 550 nm decreases. These changes are due to the escape of water bonded on two non-bridging oxygens, as well as to the hydrolysis of the melt and oxidation of divalent magnanese. The role of modifiers is also pointed out.The authors would like to express their gratitude to Dr. L.Pajasov á, E.Linhartová and M.Frýbová for careful measurements and PhMr K.ermák for the performing of solubility measurements.     

The luminescence properties of SmD and EuTTA

The results of measuring the absorption and emission spectra, decay time and quantum yield of the luminescence of SmD and EuTTA as a function of temperature (in a 77K–300K interval) and concentration are discussed. The energy transfer from the molecule organic part to the rare earth ion and the influence of nonradiative transitions are studied.The authors express their appreciation of the careful assistance in preparing the chelates given by Miss. H. Voka'lová and Mr. J. Voráek.