Vibrational Properties of Non‐Crystalline Solids

Böttger, H.

doi:10.1002/pssb.2220620102

Cited by 48 publications

(23 citation statements)

References 176 publications

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“…( [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] in good functional agreement with experimental data and a previous handwaving derivation. The total tunneling Gruneisen parameter (Equa tion (1-13)) can be evaluated using the mean-value theorem as…”

Section: Gruneisen Theorysupporting

confidence: 80%

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Thermal expansion of glasses at low temperatures

Lyon

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INFORMATION TO USERSThis material was produced from a microfilm copy of the original document. White the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted.The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction.

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Section: Gruneisen Theorysupporting

confidence: 80%

“…Several theories (5)(6)(7)(8)(9)(10)(11)(12)(13) have been proposed to explain the unusual thermal behavior of glasses at low temperature, with the simple postulate of a slowly varying continuous distribution in energy of two level states (14)(15)(16)(17) giving the best agreement with existing experimental data.…”

mentioning

confidence: 99%

Thermal expansion of glasses at low temperatures

Lyon

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“…A random variation of the change in force constants (DYSON, 1953;TAKENO and GODA, 1972; and references therein) seems more applicable to amorphous substances which we do not wish to deal with here. A review on amorphous materials has been given by BOTTGER (1974) andCONNELL (1975), see also the conference proceedings edited by LUCOVSKY and GALEENER (1976).…”

Section: Concentration Effectsmentioning

confidence: 99%

Vibrational Infrared and Raman Spectra of Non-Metals

Bilz¹,

Strauch²,

Wehner³

1984

Light and Matter Id / Licht Und Materie Id

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The vibrational properties of crystals determine the photon infrared absorption, inelastic neutron scattering and, to a large extent, inelastic photon scattering by phonons, i.e., Raman scattering. The interpretation of infrared and Raman spectra requires, therefore, an understanding of the basic features of lattice dynamics. The quantum theory of solids describes the crystal properties in terms of elementary excitations and their mutual interactions. Dynamic properties are represented by phonons (lattice vibrations) and their interactions mainly with other phonons (anharmonicity), electrons (electron-phonon coupling), and photons (interaction with radiation). This characterizes the scope of the article. Its emphasis is on the interrelation between theory and experiment, i.e., on the microscopic or model interpretation of experimental spectra.Work on infrared absorption and Raman scattering of non-metallic solids was summarized twenty years ago in two review articles in this Encyclopedia by LECOMTE (1958) and by MIZUSHIMA (1958). Since then, many important new experimental data have become available, thanks to very refined techniques for measuring spectra of pure and imperfect single crystals. Furthermore, the theory of the interactions of phonons and photons has been much improved, stimulated by the remarkable development of the theory of lattice vibrations and the mathematical techniques of many-body physics.In this article we describe the dispersion and absorption of infrared radiation and Raman scattering in non-metallic crystals, both perfect and containing point defects. At present, quantitative calculations are usually restricted to diatomic crystals, especially those with simple structures such as the alkali halides or germanium and its homologues, since our knowledge of lattice vibrations is still rather poor for polyatomic and low-symmetry crystals. The theory of lattice vibrations, as reviewed by COCHRAN and COWLEY (1967) in Vol. XXV /2a of this Encyclopedia, constitutes the background and the natural starting point for our investigations. There are other recent reviews by LUDWIG (1967), COCHRAN (1971), MARADUDIN et al. (1971), SINHA (1973), and several articles in: HORTON and MARADUDIN (eds., 1974). A summary of the developments during the last few years is given in Chap. B.An important part of the theory of lattice vibrations is the construction of models. A good example is the so-called shell model for phonons (see Sect. 4) which describes the adiabatic linear electron-ion interaction in terms of localized charges and coupling constants. This provides a natural explanation of some long-range ion-ion forces in insulators in terms of induced dipole forces. Anharmonic extensions of this shell model and its modifications seem very desirable, and first attempts in this direction are discussed.Models can often give a qualitatively and sometimes quantitatively correct description of certain processes in terms of a few parameters. They provide, therefore, an orientation for microscopic approaches. Furthermo...

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“…l) This statement may be proved by evaluating the complete time dependence of that part of the interband current (12) which is linear both in the interaction with the phonons and the incident wave (lo), (11). Calculating the corresponding matrix elements in the basis of the eigenfunctions of the operator (9) and taking the Fourier t,ransform one finds <2. '…”

Section: A Hmentioning

confidence: 99%

On the Theory of Resonance Raman Scattering in Disordered Semiconductors

Esser

1978

Physica Status Solidi (b)

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Using the Green's function technique a general expression of the one-phonon resonance Raman scattering cross-section is derived. This expression may be used to calculate the influence of a slowly varying random field present in the electronic subsystem on the resonance dependence. The theory is applied to the case of a fluctuating gap and internal random electric field. Local scattering amplitudes are obtained and the configurational average of the product of the scattering amplitudes is investigated. It is shown that this two point average effectively reduces to the averaging of the scattering amplitudes with one point distribution functions.Mittels der Methode der Greenschen Funktionen wird ein allgemeiner Ausdruck fur den Streuquerschnitt der Ein-Phonon-Resonanz-Ramanstreuung abgeleitet. Dieser Ansdruck kann zur Berechnung des Einflusses eines langsam veranderlichen im elektronischen Untersystem wirk-=men zufalligen Feldes auf die Resonanzabhiingigkeit benutzt werden. Die Theorie wird auf den Fall einer fluktuierenden Energieliicke und den ekes zufllligen inneren elektrischen Peldes angewandt. Es egeben sich lokale Streuamplituden, und das Konfigurationsmittel iiber ihr Produkt wird untersucht. Es wird gezeigt, daB dieses Zwei-Punkte-Mittel sich effektiv auf die Mittelung der Streuamplituden mit Ein-Pnnkt-Verteilungen reduziert.

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Vibrational Properties of Non‐Crystalline Solids

Cited by 48 publications

References 176 publications

Thermal expansion of glasses at low temperatures

Thermal expansion of glasses at low temperatures

Vibrational Infrared and Raman Spectra of Non-Metals

On the Theory of Resonance Raman Scattering in Disordered Semiconductors

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