Effects of Uniaxial Stress and Electric Fields on Localized Vibrational Modes

Hayes, W; Macdonald, H.F.; Elliott, R. J.

doi:10.1103/physrevlett.15.961

Cited by 23 publications

(4 citation statements)

References 3 publications

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“…uniaxial pressure. From an experiment with sttress applied in the [loo] direction the kotropic compression effect was calculated, starting from the band splitting observed with polarized light in the [loo] and [OlO] directions [3]. The result was in satisfying agreement with our relation baove, giving a factor 3.6 instead of 3.3.…”

Section: Dependence 01 the Line Position En The Lattice Constantsupporting

confidence: 68%

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Barth

Fritz

1967

Physica Status Solidi (b)

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The local mode absorption bands of U-centres are affected by the presence of alkali or halogen foreign ions in the host lattice in the following ways: a) new bands appear, which are displaced to higher and lower frequencies b) the entire spectrum undergoes a concentration-dependent shift and broadening. These effects are studied for U-centres in KC1 :Rb+, KCl: Na+, KCI :Br-, RbCl : K+, KBr : Rb+ and RbBr : K+ with doping concentrations between and 10-1. Groups of new lines can be attributed to U-centres having doping ions in the next three shells of neighbouring ions. The intensities of these lines are slightly greater than expected from the statistical probabilit,ics for such configurations. The splitting observed in a characteristic pair of lines compares favourably with a simple ealculation for the case of a C-centre perturbed by a foreign cation in a nearest neigbour (100) position. The relation between the lattice constant and local mode frequency obtained in mixed crystals may be used to discuss lattice relaxation near U-centres and "quasiharmonic" temperature-dependent band shifts.Durch Alkali-oder Halogenfremdionen in Alkalihalogenid-Einkristallcn wird das Absorptionsspektrum der lokalisierten U-Zentren-Schwingung folgendermaBcn verandert: a) Es treten neue Banden mit erhohter und erniedrigter Frequenz auf. b) Alle Banden werden, in Abhiingigkeit von der Konzentration der Fremdionen, verschoben und vcrbreitart. Diese Heobachtungen wurden an U-Zentren in den Kristallen KCI : Rb+, KCl: Na+, KCI: Br-, RbCl : K+, KBr: Rbf und RbBr: Kf gemacht. Die Fremdionenkonzentrationen lagen zwischen 10-3 und 10-1. Die neuen Linien konnen auf U-Zentren zuriickgefiihrt werdcn, die von Fremdionen in den drei nachsten Nachbarschalen geswrt werden. Die beobachteten Intensitiiten sind etwas groBer, als auf Grund der Wahrscheinlichkeit der entaprechenden Konfigurationen im Pall statistischen Einbaus zu erwarten ware. Eine fur den Fall der Stiirung durch ein Fremdion unter den nachsten Nachbarn durchgefuhrte Modellrechnung orgibt gute Ubercinstimmung mit der beobachteten Aufspaltung des entsprechenden Linienpaars. Der gefundene Zusammenhang zwischen Frequenzverschiebung und Gitterkonstante in Misehkristallen gestattet eine Abschiitzung temperaturabhangiger ,,quasiharmonischer" Frequenzverschicbungen und der Gitterrelaxation in der Nahe des U-Zentrums.Substitutional H-ions a t anion sites in alkali halides introduce an infrared active local mode vibration, which is threefold degenerated in otherwise unperturbed crystals. I n this paper we report on the perturbation of this local mode absorption by foreign cations and anions. Such'effects were observed for the fbst time by Schafer [l], who found sharp new peaks, displaced to higher and lower frequencies from the strong local mode resonance peak near 500 cm-l in KCI : Rb' .

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Section: Dependence 01 the Line Position En The Lattice Constantsupporting

confidence: 68%

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Barth

Fritz

1967

Physica Status Solidi (b)

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“…The difference between this frequency and the value of 1332 cm-I determined directly from Raman scattering (see, for example, Krishnan 1946) was tentatively attributed to an electric field-induced shift in frequency of the long-wavelength optical modes. Due to anharmonic effects some shifting with electric field is to be expected, and has previously been observed in somewhat different circumstances (Hayes et al 1965). We have therefore investigated this effect more fully by measuring the frequency of the induced band as a function of the applied field.…”

Section: Infra-red Electro-optical Effects In Diamondmentioning

confidence: 71%

Submillimeter lasing transitions in isotopic modifications of SO₂

Bugaev¹,

Shliteris²

1984

Sov. J. Quantum Electron.

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“…The shift of local modes has been investigated by HAYES and MACDONALD (1967);HAYES et al (1965b);FRITZ et al (1968);BAUERLE and HUBNER (1970);and DOTSCH (1969a). Pressure experiments on resonant modes have been performed by SIEVERS (1966, 1968); KAHAN and SIEVERS (1971);and KAHAN et al (1976); see also BENEDEK and NARDELLI (1966a);BUSSE et al (1968);BUSSE and HAIDER (1970);TIMMESFELD (1970);and GEN-ZEL et al (1969).…”

Section: Mpp'mentioning

confidence: 96%

“…Electric-field-induced frequency shifts of localized modes were first observed by HAYES et al (1965b) andMACDONALD (1967). The Stark effect of resonant modes has been observed SIEVERS, 1968, 1970;CLAYMAN and SIEVERS, 1968b;CLAYMAN et aI., 1971).…”

Section: Llrr(wr +W+»llrr(wr -W_)mentioning

confidence: 97%

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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Effects of Uniaxial Stress and Electric Fields on Localized Vibrational Modes

Cited by 23 publications

References 3 publications

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Submillimeter lasing transitions in isotopic modifications of SO₂

Vibrational Infrared and Raman Spectra of Non-Metals

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Effects of Uniaxial Stress and Electric Fields on Localized Vibrational Modes

Cited by 23 publications

References 3 publications

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Local Mode Absorption by U‐Centres in Alkali‐Halide Mixed Crystals

Submillimeter lasing transitions in isotopic modifications of SO2

Vibrational Infrared and Raman Spectra of Non-Metals

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Submillimeter lasing transitions in isotopic modifications of SO₂