Behavior of thermal phonons in amorphous media from 4 to 300 K

The intensity, frequency shift, and linewidth of the longitudinal Brillouin lines have been measured from 4 to 300 K in crystal quartz, fused quartz, and borosilicate glass. Differences in intensity between Stokes and anti-Stokes components have been found, extending to low temperatures the observation of long-lived vibrational states with occupation numbers equal to $({e^{\frac{h\nu }{\mathrm{kT}}}-1)}^{-1\mathrm{}}$. Some anomalies in the frequency dependence of the elastic properties of fused quartz are eliminated. The measurements of the attenuation, which modify previous results between 77 and 300 K, are in good agreement with stimulated Brillouin scattering measurements below 10 K.