Spectra of Hydrogenated Calcium Fluoride Containing Rare-Earth Ions

Jones, G. D.; Peled, Shahar; Rosenwaks, Salman; Yatsiv, S.

doi:10.1103/physrev.183.353

Cited by 48 publications

(20 citation statements)

References 24 publications

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“…All the available evidence suggests that H-ions may substitute for Fions in a variety of defects involving cation impurities. Analogues which have been identified so far are (i) RE"-H; for RE3+-F; (Jones et al 1969), (ii) RE2+F; Hfor RE2+F; (Chambers and Newman 1971b) and (iii) RE3+0:-H-for RE3+O;-F- (Chambers andNewman 1971a, Reddy et a1 1971). A notable omission from this list is the analogue of the trigonal T, centre which has the structure RE3+ 02-F; (Reddy et al 1971), and is a defect which is commonly found in crystals in high concentrations.…”

Section: Summary and Discussionmentioning

confidence: 90%

“…In oxidized pulled crystals which contained a high concentration of Q and S centres, there was no detectable local mode absorption from H-ions in interstitial sites (Jones et a/ 1969); it is therefore deduced that these defects involve substitutional H-ions. The observation of three fundamental transitions for both the Q and S centres implies that the Hions in those complexes occupy sites which have lower than axial symmetry.…”

Section: Summary and Discussionmentioning

confidence: 95%

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Self-Focusing and Waveguide Propagation in a Plasma

Litvak¹

1973

Sov. Phys. Usp.

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When hydrogen is diffused into calcium fluoride crystals which contain a rare earth impurity and a relatively low concentration of oxygen two types of RE3--H-complexes of lower than axial symmetry are formed. These centres have been detected by measurements of the infrared absorption .from the localized vibrations of the paired H-(or D-) ions. In crystals containing Ce3+ ions, a new EPR spectrum has been observed which correlates with one of these centres. Models for the centres are discussed. and it is suggested that one may be a simple,modification of the trigonal (T,) centre R E 3 -0 2 -F ; , where one of the Fions is replaced by an Hion.

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Section: Summary and Discussionmentioning

confidence: 90%

Section: Summary and Discussionmentioning

confidence: 95%

Self-Focusing and Waveguide Propagation in a Plasma

Litvak¹

1973

Sov. Phys. Usp.

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“…It is generally accepted that the larger width of the Z mode is, in part, a consequence of one-phonon decay through phonons whose energy is the separation of these two modes. As the infrared data did not reveal any simple regularity with energy separation along the R 3+ series, this one-phonon decay mechanism was considered to be just one contribution to the observed low-temperature residual line widths [1]. The presence of inhomogeneous broadening was inferred from the observation that the larger the mismatch of the R 3+ and Ca 2+ ionic radii, the larger was the corresponding Z mode line width.…”

Section: Introductionmentioning

confidence: 99%

“…The principal site for all R 3+ ions in CaF 2 and those up to Dy 3+ in SrF 2 has tetragonal (C 4v ) symmetry, with the H -ion located in the nearest interstitial <100> site. [1] Its infrared-absorption spectrum comprises two H -local-mode lines in the 1000 cm -1 (10 µm) spectral region whose energy separation decreases along the R 3+ series from 140 cm -1 for La 3+ to 30 cm -1 for Lu 3+ . The lower-frequency line is the tranverse (X,Y) local-mode and the higherfrequency mode is the longitudinal Z local-mode.…”

Section: Introductionmentioning

confidence: 99%

Free electron laser studies of local mode linewidths in SrF ₂ :Gd ³⁺ :H ^–

Wells

Jones

Carder

et al. 2004

phys. stat. sol. (c)

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Infrared-absorption lines of the (X,Y) and Z local modes of hydrogenic C4v centres in rare-earth doped CaF2 and SrF2 have differing 10K linewidths, attributed in part to one-phonon decay from the upper to the lower frequency local mode. However for SrF2 the lower frequency (Z) mode has the larger line width for Gd3+, Tb3+ and Dy3+ and one-phonon decay cannot be the primary cause for the differing line widths. This is borne out by free-electron laser 10K studies of the H-lines in SrF2:0.33%Gd3+, which yield (X,Y) and Z mode lifetimes of 43 and 30 ps suggesting similar homogeneous linewidths. The larger line-width for the Z mode is attributed to the greater sensitivity of this mode to rare-earth ion mismatch and to crystal disorder.

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“…U -center local modes in additively doped crystals have been observed by SCHAEFER (1960); MIRLIN and RESHINA (1966);BARTH and FRITZ (1967);YATSIF et aL (1967);JONES et aL (1968JONES et aL ( , 1969ASHBURNER et aL (1968);CHAMBERS andNEWMAN (1969, 1971a, b);CHAMBERS (1971); CASTRO et aL (1975);and KOSTER and DEN HARTOG (1977); a theoretical investigation of these defect pairs has been carried out by JASWAL (1966);STRIEFFLER and JASWAL (1969b);SCHNEIDER (1973);GUPTA (1974);and KRISHNAMURTHY and HARIDASAN (1978 Sect. 30 The Li + ion in potassium halides is known to produce a low-frequency resonance.…”

mentioning

confidence: 93%

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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Spectra of Hydrogenated Calcium Fluoride Containing Rare-Earth Ions

Cited by 48 publications

References 24 publications

Self-Focusing and Waveguide Propagation in a Plasma

Self-Focusing and Waveguide Propagation in a Plasma

Free electron laser studies of local mode linewidths in SrF ₂ :Gd ³⁺ :H ^–

Vibrational Infrared and Raman Spectra of Non-Metals

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Spectra of Hydrogenated Calcium Fluoride Containing Rare-Earth Ions

Cited by 48 publications

References 24 publications

Self-Focusing and Waveguide Propagation in a Plasma

Self-Focusing and Waveguide Propagation in a Plasma

Free electron laser studies of local mode linewidths in SrF 2 :Gd 3+ :H –

Vibrational Infrared and Raman Spectra of Non-Metals

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Free electron laser studies of local mode linewidths in SrF ₂ :Gd ³⁺ :H ^–