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Title:Infrared absorption by localized polarons in the silver halides
Author(s):Brandt, Richard Charles
Doctoral Committee Chair(s):Brown, Frederick C.
Department / Program:Physics
Subject(s):infrared absorption
localized polarons
silver halides
silver halide crystals
Abstract:The infrared absorption of silver halide crystals, induced by simultaneous illumination of the crystals with light whose energy exceeded the indirect band gap, was measured from 33 to 2000 cm-1 at temperatures from. 90 K to 40 0 K. The induced far infrared absorption was shown to be in agreement with the predictions of an extension of the theory of Buimistrov and Pekar for po1arons bound to a positive charge center. In AgBr at 9.30 K, the induced absorption at 168 cm-1 was identified as the 1s to 2p transition, and the absorpti.on at 192 ± 2 cm -1 as the ls to continuum transition. In AgC1 at 9.30 K, the corresponding transitions were at 272 cm and at 292 ± 3 cm The induced infrared absorption at higher frequencies was shown to be phonon side bands of the far infrared. absorption. In the process of calculating the above transitions, the Buimistrov-Pekar expression for the polaron self energy was evaluated in a new manner. The results showed that for coupling constants O! less than 6, the Buimistrov-Pekar formulation gives a lower value of self energy than other polaron theories. The longitudinal optical frequencies in AgBr and AgCl were measured directly for the first time at low temperatures using a variation of the technique of Berreman. At 7oK, the longitudinal optical frequency was 140 ± 1 cm- l in AgBr, and 197 ±l cm-1 in AgCl.
Issue Date:1967
Genre:Dissertation / Thesis
Rights Information:1967 Richard Charles Brandt
Date Available in IDEALS:2011-07-08
Identifier in Online Catalog:6090090

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