Infrared absorption by localized polarons in the silver halides

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Brandt, Richard Charles

Contributors dc:contributor

• Brown, Frederick C.

• infrared absorption
• localized polarons
• silver halides
• silver halide crystals

Statement dc:rights

• 1967 Richard Charles Brandt

Language dc:language

en

Identifier

6090090

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25716