Model for Brillouin Scattering in Amorphous Solids

TLDR: In this paper, an elastic continuum model for Brillouin scattering by an amorphous solid is presented, where light scatters on distorted plane wave acoustic phonons leads to the prediction that the scattered intensity plotted as a function of the frequency transfer Ωo consists of the usual BrillouIN peaks plus a background which, a t room temperature, goes like Ω; for small Ω o, but rises less steeply for larger Ω O, and may even bend over within the range of the validity of the model, depending on the correlation lengths for spatial fluctuations due

Abstract: An elastic continuum model is presented for Brillouin scattering by an amorphous solid. The assumption that light scatters on distorted plane wave acoustic phonons leads to the prediction that the scattered intensity plotted as a function of the frequency transfer Ωo consists of the usual Brillouin peaks plus a background which, a t room temperature, goes like Ωo; for small Ωo, but rises less steeply for larger Ωo, and may even bend over within the range of the validity of the model, depending on the correlation lengths for spatial fluctuations due to disorder and on the speeds of sound. For the case of a-Si, additional results are obtained with the help of existing experimental measurements. Es wird die Brillouinstreuung in a morphen Snbstanzen an einem elastischen Kontinuums-modell diskutiert. Die Annahme, das Licht an durch deformierte ebene Wellen beschriebenen akustischen Phononen gestreut wird, fiihrt zu folgenden Aussagen. Die Streuintensitiit als Funktion der Frequenzverschiebung besteht aus den ublichen Brillouin-Peaks und einem Hintergrund, der, bei Raumtemperaturen, fur kleine Ωo proportional zu Ω 2o ist. Mit wachsendem Ω o wachst der Hintergrund dam schwacher als Ω2o. Jc nach den Werten der Korrelationslangen fur raumliche Fluktuationen und der Schallgeschwindigkeiten kanner im Giiltigkeitsbereich des Modells sogar nach Erreichen eines Maximums wieder abfallen. ZusaItzliche Aussagen werden fur den Fall von a-Si unter Ausnutzung existierender Messungen gemacht.