PHONONS IN THE MIXED-CRYSTAL SYSTEM KCl-KBr.
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Date
1967
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Several bulk mixed crystals of KCl-KBr have been measured by means of their infrared reflectance at $300^{\circ}K, 200^{\circ} K$ and $100^{\circ} K$ from $25-250 cm^{-1}$. Only one major restrrahlen peak was observed in each case which shifted linearly with concentration. It is apparent that other modes are present and contribute to the broad reststrahlen band but their oscillator strengths are small compared with the main lattice vibration. The reflectivity curves were analyzed by means of a Kramers-Kronig transformation and a classical oscillator model to provide the oscillator strengths and damping constants. Transmission measurements of thin evaporated films and of the materials in polyethylene matrices were in good agreement with the reflection data.
Description
The research of the Spectroscopy Laboratory is sponsored in part by the National Science Foundation Grant No. GP-4923. Work in the Research Laboratory of Electronics was supported in part by Air Force Cambridge Research Laboratories under Contract AF19(628)--6066 and the Joint Services Electronics Program (Contract DA28-043-AMC 02536(E)). Present address of Jeanne H. Fertel: N.A.S.A., Electronics Research Center, Cambridge, Mass.
Author Institution: Spectroscopy Laboratory and Research Laboratory of Electronics, Massachusetts Institute of Technology
Author Institution: Spectroscopy Laboratory and Research Laboratory of Electronics, Massachusetts Institute of Technology