Observation of the onset of strong scattering on high frequency acoustic phonons in densified silica glass

TL;DR

This study investigates the high-frequency behavior of acoustic phonons in densified silica glass, revealing a transition to strong scattering likely caused by resonance with boson-peak modes rather than disorder-induced Rayleigh scattering.

Contribution

It provides new insights into the scattering mechanisms of high-frequency acoustic phonons, highlighting the role of boson-peak mode hybridization in densified silica glass.

Findings

Linewidth increases with frequency to a power alpha ≥ 4

Strong scattering occurs at a crossover frequency

Resonance with boson-peak modes is a probable cause

Abstract

The linewidth of longitudinal acoustic waves in densified silica glass is obtained by inelastic x-ray scattering. It increases with a high power alpha of the frequency up to a crossover where the waves experience strong scattering. We find that \alpha is at least 4, and probably larger. Resonance and hybridization of acoustic waves with the boson-peak modes seems to be a more likely explanation for these findings than Rayleigh scattering from disorder.