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  • 1
    Electronic Resource
    Electronic Resource
    Time-resolved XEOL spectroscopy of new scintillators based on CsI : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 806-809 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Spectral and kinetic properties of the fast intrinsic ultraviolet luminescence of CsI single crystals either pure or doped by Br, Cl, Rb, or K, studied under different types of excitation at temperatures from 80 to 550 K, are presented. Since conventional models of intrinsic luminescence in their "pure'' form fail to explain the observed properties of the UVL, a new one should be worked out taking into account collective interaction of neighboring excitations and defects, created by ionizing particles, which form clusters of excitations. It has been shown that luminescence decay time can be controlled by doping with homologs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142614
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Electromagnetic excitation of ultrasound in magnetically ordered dielectrics (1997)
    Springer
    Journal of experimental and theoretical physics 84 (1997), S. 990-993 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electromagnetic excitation of sound in magnetically ordered dielectrics—ferro-and antiferromagnets—is investigated theoretically. It is shown that sound generation in dielectrics by the Lorentz mechanism (displacement current) is much less efficient than in metals. The magnetoelastic mechanism of sound excitation in dielectrics is just as efficient as in metals. In antiferromagnets the amplitude of the excited sound depends on the relaxation parameter in the magnetic subsystem. The sound excitation efficiency increases as the orientational phase transition point or the ferromagnetic resonance frequency is approached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558190
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  • 3
    Electronic Resource
    Electronic Resource
    Theory of X-ray photoacoustic spectroscopy (1995)
    Springer
    Applied physics 60 (1995), S. 333-341 
    Details
    ISSN: 1432-0630
    Keywords: 78.70.Dm ; 78.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract PhotoAcoustic Spectroscopy (PAS) in the X-ray region is becoming a new field in PAS research and poses some new problems, such as heat production mechanisms and non-exponential heat distribution due to multi-excitation processes, additional signals caused by escaped fluorescence and electrons, special backing and fronting setup for comparison with absorption experiment, etc. In this paper we treat these problems and include them in an extended theoretical model which can be reduced to the RG model in a special case. The results indicate that the non-exponential heat distribution has no effect on the PA phase. The contribution by gas heating of the escaped electrons can be neglected. The thermally thin gas layers between the sample and the Be windows are sensitive factors to both amplitude and phase. The PA signal generated in the backing gas layer by the backing surface of the sample should be considered to understand the frequency dependence of the PA signal. The expansion of the backing gas layer is the reason for the phase change in PA-EXAFS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538414
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of X-ray photoacoustic spectroscopy (1995)
    Springer
    Applied physics 60 (1995), S. 333-341 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.70.Dm; 78.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. PhotoAcoustic Spectroscopy (PAS) in the X-ray region is becoming a new field in PAS research and poses some new problems, such as heat production mechanisms and non-exponential heat distribution due to multi-excitation processes, additional signals caused by escaped fluorescence and electrons, special backing and fronting setup for comparison with absorption experiment, etc. In this paper we treat these problems and include them in an extended theoretical model which can be reduced to the RG model in a special case. The results indicate that the non-exponential heat distribution has no effect on the PA phase. The contribution by gas heating of the escaped electrons can be neglected. The thermally thin gas layers between the sample and the Be windows are sensitive factors to both amplitude and phase. The PA signal generated in the backing gas layer by the backing surface of the sample should be considered to understand the frequency dependence of the PA signal. The expansion of the backing gas layer is the reason for the phase change in PA-EXAFS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538414
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Electromagnetic generation of ultrasound in antiferromagnets (1997)
    Springer
    Physics of the solid state 39 (1997), S. 807-809 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The generation of ultrasound in semi-infinite, collinear, two-sublattice antiferromagnetic metals is investigated theoretically. Two cases are considered: 1) when relaxation in the magnetic subsystem is so rapid that variations of the ferromagnetism and antiferromagnetism vectors cannot keep pace with the variation of the displacement vector and the electromagnetic field vectors; 2) when the opposite is true. It is shown for the first time that in either case only transverse sound is excited at low temperatures in zero static magnetic field, and only longitudinal sound is excited at high temperatures in the vicinity of the Néel point. It is also shown that in antiferromagnets, as opposed to ferromagnets, linear sound generation takes place in zero static magnetic field, and the efficiency of contactless sound generation is generally weaker.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1129974
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  • 6
    Electronic Resource
    Electronic Resource
    Appearance of new lines and change in line shape in the IR spectrum of a NaV2O5 single crystal at a spin-Peierls transition (1997)
    Springer
    JETP letters 65 (1997), S. 743-748 
    Details
    ISSN: 1090-6487
    Keywords: 78.30.Er ; 75.30.Kz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New lines are observed in the infrared spectrum of a crystal due to unit-cell doubling at a spin-Peierls transition (in NaV2O5). The change in the shape of the spectral lines at the spin-Peierls transition is recorded. A contour characteristic of a Fano resonance is observed above the transition temperature T sp and the standard symmetric contour is observed below T sp . We attribute this effect to the opening of a gap in the magnetic-excitation spectrum at the spin-Peierls transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567420
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetic resonance in pure and diamagnetically diluted spin-Peierls CuGeO3 (1996)
    Springer
    JETP letters 64 (1996), S. 305-311 
    Details
    ISSN: 1090-6487
    Keywords: 76.50.+g ; 75.50.Kj ; 75.30.G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magnetic resonance at frequencies 22–75 GHz is investigated in pure single-crystalline CuGeO3 in the temperature range 1.2–25 K. At temperatures below 4 K the magnetic resonance line splits into four spectral components. The line close to the ESR of the paramagnetic phase is associated with impurities or defects. The other three lines have the same intensity in different samples and are apparently characteristic for pure single crystals at low temperature. An antiferromagnetic resonance with two resonance absorption branches and a spectrum characteristic for an antiferromagnet with easy, average, and hard anisotropy axes was observed and investigated in the Néel compound Cu0.98Zn0.02GeO3 with diamagnetic dilution of the spin subsystem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567188
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  • 8
    Electronic Resource
    Electronic Resource
    ESR millimeter-band spectroscopy of magnetic ordering in the low-dimensional magnet CuGeO3 (1997)
    Springer
    Journal of experimental and theoretical physics 85 (1997), S. 943-948 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Resonant absorption of microwaves in CuGeO3 single crystals in a frequency band of 40 to 120 GHz, in magnetic field B⩽15 T, at temperatures ranging between 0.5 and 300 K, and in the configuration B∥a has been investigated. Several absorption lines (S 0, S a, and S b) whose parameters strongly depend on temperature have been detected close to ESR. The temperature dependence of the total absorption in the main line S 0 with the Landé g-factor g 0=2.154 at temperatures above the spin-Peierls transition temperature is in good agreement with Bonner and Fisher’s theoretical prediction for a one-dimensional Heisenberg spin chain. In addition to the main resonance, a resonance of smaller amplitude, S a, with the g-factor g a=2.72 has been detected at temperatures ranging down to a characteristic temperature T≃1 K, below which the amplitude of this feature drops to zero. A radical restructuring of the magnetoabsorption spectrum occurs at the temperature of the spin-Peierls transition T SP≈14 K. At T〈12 K new features emerge in the spectrum, namely, a broad absorption line overlapping with the narrow lines S 0 and S a, and a line S b with g b=1.83, which is not detected at temperatures above T SP. An analysis of amplitudes and total absorption of ESR lines as functions of temperature has shown that the temperature range below 1 K is anomalous, which may be caused by an additional ordering in the CuGeO3 magnetic subsystem at low temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558399
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  • 9
    Electronic Resource
    Electronic Resource
    Dispersion of the speed of sound and absorption in the vicinity of the liquid-gas critical point: Renormalization-group calculation in the two-loop approximation (1998)
    Springer
    Journal of experimental and theoretical physics 87 (1998), S. 934-943 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The renormalization group method to second order in the ε expansion is used to calculate the singular parts of the absorption and dispersion of the speed of sound on the critical isochor above T c. We express the investigated quantities in terms of the response function to temperature variations in the H model of Halperin, Hohenberg, and Siggia. Results are compared with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558742
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  • 10
    Electronic Resource
    Electronic Resource
    Nonequilibrium paramagnetic susceptibility of gallium impurity centers in lead telluride (1998)
    Springer
    Journal of experimental and theoretical physics 87 (1998), S. 1009-1013 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The temperature dependences of the resistance and magnetic susceptibility are studied in gallium-doped lead telluride, which is characterized by a delayed photoconductivity effect, under various illumination conditions. After a sample is illuminated at low temperatures, the magnetic susceptibility is diamagnetic in the region of metallic delayed conductivity (for T〈=0 K). In the region of thermodynamic equilibrium (T〈70 K), where conductivity is activational, the magnetic susceptibility is likewise diamagnetic and essentially equals the low-temperature value. A paramagnetic susceptibility peak is observed in the transitional region (T∼50–70 K), where the conductivity is of a nonequilibrium character but the carriers are still nondegenerate. This peak increases in magnitude with the rate of measurements in the indicated temperature range. In addition, a paramagnetic variation of the susceptibility following the Curie law is observed with uncontrollable (weak) illumination from the cryostat cap at low temperatures (T〈25 K). The interpretation of the observed dependences is based on notions of variable valence of gallium in lead telluride, while the appearance of a paramagnetic susceptibility peak is attributed to the presence of shallow localized levels of gallium in a trivalent state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558728
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