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On the optical absorption of free polarons at weak coupling
Author(s) -
Devreese J.,
Huybrechts W.,
Lemmens L.
Publication year - 1971
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220480104
Subject(s) - polaron , attenuation coefficient , perturbation (astronomy) , dissipation , feynman diagram , atomic physics , absorption (acoustics) , physics , formalism (music) , effective mass (spring–mass system) , chemistry , condensed matter physics , molecular physics , quantum mechanics , optics , electron , art , musical , visual arts
The optical absorption of Frohlieh polarons as a function of the frequency of the incident light is calculated within the Lee‐Low‐Pines formalism. A simple calculation, which is developed here in full detail, gives a result for the absorption coefficient which is exact in order a. Gurevich et al. [1] had obtained this perturbation result using involved calculations based on Green's functions. This result is also extracted here from the “dissipation” calculation of Feynman ct al. [2]. An analytical expression for the optical absorption between 0 < α < 1 is proposed. For α = 1 the main correction to the perturbation result is e decrease of about 15% around the maximum of the absorption. This seems to explain the difference between the experimental absorption detected in CdO (α = 0.75) by Finkenrath et al. [14] and the perturbation result. The effect of a static electric field on the optical absorption coefficient is examined. For low temperatures a shift towards lower frequencies of the threshold for absorptiou is predicted. This shift depends on the mobility and effective mass of the polaron.