Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Poster II

DY 30.39: Poster

Donnerstag, 29. März 2007, 16:00–18:00, Poster D

Theory of Low-Frequency Raman-Spectroscopy in Disordered Solids — •Bernhard Schmid and Walter Schirmacher — Phys.-Dept. E13, Technische Universität München, D-85747 Garching, Germany

Raman spectra of disordered solids in the regime near 50 wavenumbers show very often an intensity maximum ("boson peak"). According to a theory of Shuker and Gammon the intensity is proportional to the vibrational density of states (DOS), divided by the frequency squared. The existing data, however do not agree with DOS data measured e.g. by neutron inelastic scattering. We present a theory of vibrational excitations in disordered solids [1] and their observation by Raman spectroscopy, based on the assumption that the elastic moduli and the opto-elastic coupling constants (Pockels constants) fluctuate in space. Comparing our theory with experimental data gives not only good agreement, but enables us to compare with other related anomalous vibrational properties such as neutron and synchrotron radiation spectra, as well as specific heat and thermal conductivity data.

[1] W. Schirmacher, Europhys. Lett. 73, 892 (2006)