Spectroscopy of Phonon Scattering in Glass

Abstract
This Letter investigates the phonon scattering in SiO2 glass at frequencies above 100 GHz by phonon spectroscopy with superconducting tunnel junctions. By analyzing the frequencies of the scattered phonons with two independent techniques, evidence is obtained for strong inelastic phonon scattering in glass. Furthermore, the phonon mean free path is determined as a function of the phonon frequency.