Hyper-Raman scattering from vitreous boron oxide: coherent enhancement of the boson peak

TL;DR

This study investigates hyper-Raman scattering in vitreous B$_2$O$_3$, revealing a significant coherent enhancement of the boson peak linked to structural unit vibrations, advancing understanding of vibrational properties in glasses.

Contribution

It demonstrates the coherent enhancement of hyper-Raman signals in vitreous B$_2$O$_3$ and relates the boson peak to specific structural unit librations, providing new insights into vibrational dynamics.

Findings

Hyper-Raman signal is coherently enhanced compared to Raman.

Boson peak relates to out-of-plane librations of structural units.

Hyper-Raman strength is comparable to cooperative polar modes.

Abstract

Hyper-Raman scattering spectra of vitreous B$_2$O$_3$ are reported and compared to Raman scattering results. The main features are indexed in terms of vibrations of structural units. Particular attention is given to the low frequency boson peak which is shown to relate to out-of-plane librations of B$_3$O$_3$ boroxol rings and BO$_3$ triangles. Its hyper-Raman strength is comparable to that of cooperative polar modes. It points to a sizeable coherent enhancement of the hyper-Raman signal compared to the Raman one. This is explained by the symmetry of the structural units.