About the origin of the boson peak in vitreous silica

Abstract

The long-standing issue of the boson peak in vitreous silica is revised in the light of new considerations about its nanometric structure. The shoulder at 7.5 nm⁻¹ that is visible in the structure factor of vitreous silica is an indication that there exists a quasiperiodicity with a period close to 1 nm. Using the results obtained earlier by inelastic X-ray scattering, it is deduced that the boson peak observed by inelastic light or neutron scattering in vitreous silica corresponds to a van Hove singularity associated with the Brillouin zone limit of a transverse acoustic band. This Brillouin zone is related to the quasiperiodicity revealed by the 7.5 nm⁻¹ correlation peak.