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Collective Excitations in Microcrystal Aggregates and Composites
Author(s) -
Monecke J.
Publication year - 1989
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.2221550212
Subject(s) - phonon , microstructure , raman spectroscopy , aggregate (composite) , materials science , dielectric , absorption (acoustics) , polar , spectral line , condensed matter physics , composite material , dielectric function , quasiparticle , molecular physics , optics , chemistry , physics , quantum mechanics , optoelectronics , superconductivity
The optical properties of aggregates of microcrystals are dominated by surface excitations. The Raman and ir absorption spectra of polar microcrystals show, however, peaks at the bulk TO‐phonon frequencies, too, the occurrence of which depends on the sample preparation, i.e. on the aggregate microstructure. A recently developed theory for the dielectric function of composites of different topologies is applied to the calculation of the phonon spectra. It is shown that this theory explains the occurrence of bulk TO‐phonon peaks in appropriate microstructures.