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Theory of Second‐Order Resonance Raman Scattering in the Case of Strong Excitonic Effects
Author(s) -
Bechstedt F.,
Haus D.
Publication year - 1978
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.2220880119
Subject(s) - raman scattering , x ray raman scattering , resonance (particle physics) , exciton , phonon , atomic physics , scattering , physics , condensed matter physics , coulomb , raman spectroscopy , electron , chemistry , quantum mechanics
Calculations of the integral and differential cross‐section of the two‐phonon resonance Raman scattering are presented. Both the cases of Q ‐independent deformation and Q ‐dependent Fröhlich electron–one‐phonon coupling are considered. The electronic intermediate states are described in the Wannier‐Mott approximation. The large binding energy limit is assumed. It is shown that the intensity of combination tones are negligible small compared to that of pure overtones if the exciton binding energy is large enough. In contrast to the case of uncorrelated electron‐hole pairs for both the allowed and forbidden scattering a pronounced double peak structure is found in the resonance behaviour of the integral cross‐section. Analogously to the case without electron‐hole Coulomb interaction the lineshape of the two‐phonon scattering depends strongly on the incident photon energy. Only far from electronic transition energies the second‐order Raman spectra can be interpreted in terms of the two‐phonon density of states. Results obtained here are in qualitative agreement with experimental observations in CdS.