Far-infrared absorption of alkali halide crystals containing H− ions

1968 ◽  
Vol 46 (20) ◽  
pp. 2263-2270 ◽  
Author(s):  
E. J. Woll Jr. ◽  
T. Gethins ◽  
T. Timusk
Keyword(s):  
Alkali Halide ◽  
Far Infrared ◽  
Local Mode ◽  
Host Crystal ◽  
Substitutional Impurity ◽  
Side Band ◽  
Alkali Halide Crystals ◽  
Localized Vibrations ◽  
Absorption Measurements ◽  
Good Agreement

The optical absorption from localized vibrations associated with the H− ion as a substitutional impurity in KBr and KI is investigated in the far infrared. A force constant model for the defect is derived from a theoretical fit of the experimental results for the anharmonic side band of the H− local mode. This model is used to predict the absorption spectrum of the defect in the far infrared below the Reststrahlen frequency. Good agreement is obtained with absorption measurements at low temperature. It is shown that some of the observed peaks correspond to localized modes, while others are directly related to van Hove singularities in the frequency spectrum of the host crystal.

Method of Gaussian quadrature in the calculation of optical absorption and magnetic circular dichroism spectra of s2 ions in alkali halide crystals: application to KBr:In+

1979 ◽  
Vol 57 (10) ◽  
pp. 1614-1623 ◽  
Author(s):  
Y. Kamishina ◽  
V. S. Sivasankar ◽  
P. W. M. Jacobs
Keyword(s):  
Circular Dichroism ◽  
Optical Absorption ◽  
Alkali Halide ◽  
Magnetic Circular Dichroism ◽  
Gaussian Quadrature ◽  
Electron Configuration ◽  
Alkali Halide Crystals ◽  
Complete Energy Matrix ◽  
Circular Dichroïsm ◽  
Good Agreement

The problem of calculating the lineshape function for optical absorption and magnetic circular dichroism due to ionic impurities with the ns2 outer electron configuration, incorporated substitutionally in alkali halide crystals, has been reformulated. The complete energy matrix has been diagonalized directly. Integration over the interaction mode coordinates of Eg and T2g symmetry has been carried out numerically using Gaussian quadrature formulae; the interaction with the A1g mode has been taken into account by the usual convolution procedure. The method has been applied to KBr:In+. The calculated lineshape functions for optical absorption at temperatures ranging from 4 to 300 K and, for MCD at 5 K, are in good agreement with the experimentally determined lineshapes. Moreover, the theory accounts very well for the observed variation of the effective g tensor for the A band with temperature. The calculated values for the moments of the absorption and MCD lineshape functions are in reasonably satisfactory agreement with those deduced from the observed spectra.

Far-Infrared Lattice Absorption in Alkali Halide Crystals

1965 ◽  
Vol 139 (4A) ◽  
pp. A1295-A1303 ◽  
Author(s):  
Rogers Stolen ◽  
Klaus Dransfeld
Keyword(s):  
Alkali Halide ◽  
Far Infrared ◽  
Alkali Halide Crystals

scholarly journals Induced Far-Infrared Absorption in Mixed Alkali Halide Crystals

1973 ◽  
Vol 8 (10) ◽  
pp. 4868-4874 ◽  
Author(s):  
C. de Jong ◽  
G. H. Wegdam ◽  
J. van der Elsken
Keyword(s):  
Infrared Absorption ◽  
Alkali Halide ◽  
Far Infrared ◽  
Mixed Alkali ◽  
Alkali Halide Crystals

Infrared absorption due to H− ions in sodium and potassium halides. II. Impurity induced absorption in the far-infrared region

1970 ◽  
Vol 48 (24) ◽  
pp. 2917-2929 ◽  
Author(s):  
R. W. MacPherson ◽  
T. Timusk
Keyword(s):  
Absorption Spectrum ◽  
Density Of States ◽  
Infrared Absorption ◽  
Far Infrared ◽  
Infrared Region ◽  
Local Mode ◽  
Defect Model ◽  
Side Band ◽  
Sodium And Potassium ◽  
Potassium Halides

Measurements and calculations of the impurity induced far-infrared absorption due to H− ions in the sodium and potassium halides are presented. The defect model which was previously determined from theoretical fits to experimental local mode and anharmonic side band data is used to predict the absorption spectrum in the far-infrared region below the reststrahlen frequency. The agreement with the observed absorption spectra is good. It is shown that certain features may be interpreted as Van Hove singularities in the unperturbed density of states of the host crystals and that other peaks in the KBr and KI spectra are due to localized resonances.

Far-infrared absorption in bulk samples of superconducting niobium and tantalum

1970 ◽  
Vol 48 (10) ◽  
pp. 1254-1258 ◽  
Author(s):  
D. Hemming ◽  
R. Sati ◽  
J. D. Leslie
Keyword(s):  
Critical Temperature ◽  
Infrared Absorption ◽  
Far Infrared ◽  
Gap Width ◽  
Absorption Measurements ◽  
Good Agreement

Measurements have been made of far-infrared absorption in bulk samples of superconducting niobium and tantalum at 1.41 °K. The results indicate a gap width 2Δ of 23.8 ± 0.2 cm−1 for niobium and 10.3 ± 0.2 cm−1 for tantalum. The measured values of the critical temperature, Tc, for these samples are 9.38 ± 0.04 °K for niobium and 4.33 ± 0.02 °K for tantalum. In terms of these values of Tc, 2Δ is 3.66 ± 0.05 kTc for niobium and 3.43 ± 0.08 kTc for tantalum. These values of 2Δ are in good agreement with those obtained by other methods, unlike earlier far-infrared absorption measurements on bulk niobium and tantalum that indicated anomalously low values of 2Δ.

Anion polarizability functions in alkali halide crystals

1997 ◽  
Vol 92 (6) ◽  
pp. 1029-1033
Author(s):  
A. BATANA ◽  
J. BRUNO ◽  
R.W. MUNN
Keyword(s):  
Alkali Halide ◽  
Alkali Halide Crystals
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