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Title:Raman scattering from the hydroxyl ion in alkali halides
Author(s):Fenner, Wayne Robert
Doctoral Committee Chair(s):Klein, Miles V.
Department / Program:Physics
Subject(s):Raman scattering
hydroxyl ion
alkali halides
argon ion laser
tandem double monochromator
photoelectric detection
Abstract:Raman scattering has been observed from the hydroxyl ion in NaCl, KCl. and KBr crystals. The measurements were made using an argon ion laser as a light source and a tandem double monochromator with photoelectric detection. The crystals were cleaved and mounted in such a way that the directions and polarizations of the incident laser light and Raman scattered light were along (100) crystalographic directions. A Raman emission attributed to the stretching motion of the OH- ion was seen in all samples.. The polarization of the Raman light was Z(X.X)Y, i. e. parallel to that of the incident light. The temperature dependence of the frequency shifts and half-widths was measured from 12 K to room temperature. Several differences between our results and infrared absorption measurements were noted. The stretching bands in KBrsOH- and KClaOH- showed no resolvable structure. However, at 15 K. the stretching band in NaClaOH- appeared to be composed of two lines separated by about 2.8 cm-1 Raman scattering from the stretching level o£ OD- doped NaCl was observed whereas no corresponding infrared absorption has been seen. Raman scattering from the librational or rocking motion of the OH- dipole was observed in KBraOH- in the temperature range of 12 K to 40 Ko In this case, the polarization of the Raman light was Z(X,Z)Y, i. e. perpendicular to the polarization of the incident light. The temperature dependence of the frequency shift and half-width agree with the results of infrared measurements made on the same system. Infrared absorption measurements have shown the existence of other energy levels in the alkali halide-hydroxyl ion system. These include the so-called "non-Devonshire" or tf30 cm- 1 ., bands, the stretching plus libration combination band 0 and the stretching plus "non~Devonshirett combination band. Any Raman scattering from a "non-Devonshire" level that may have occurred in this experiment was obscured by instrument effects, such as the presenoe of grating ghosts near the laser frequency. No Raman scattering from the stretching plus libration or stretching plus "non-Devonshire" combination levels was observed. The second order or two-phonon Raman spectra were measured for both the pure and doped alkali halides. No impurity induced Raman scattering could be definitely reorganized. We attempt to correlate some of the peaks in the two phonon Raman spectrum of KBr with combinations and overtones of the single phonon dispersion curves.
Issue Date:1969
Genre:Dissertation / Thesis
Rights Information:1969 Wayne Robert Fenner
Date Available in IDEALS:2011-07-13
Identifier in Online Catalog:6072330

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