Addendum: Frequency dependence of the phonon reflection coefficients at an interface between silicon and solid hydrogen

Abstract

The heat-pulse method has been used to investigate the frequency dependence of the reflection coefficients of phonons incident on an interface between a silicon crystal and solidified hydrogen. The reflection coefficients are found to increase with decreasing pulse temperature (and hence decreasing phonon frequency). For longitudinal phonons the reflection coefficient agrees with the acoustic-mismatch theory at a pulse temperature of ∼2 K. for transverse phonons the reflection coefficient approaches the theoretical value at the lowest pulse temperature investigated, 1.5 K.