Knowledge Bank

The Brillouin spectra of methanol and methanol-d have been determined over the frequency interval 1.5 to 6.0 gigahertz as a function of temperature. This has allowed a determination of phonon velocities, velocity dispersion, and absorption coefficients for these materials in the hypersonic range. Observed dispersions in velocity have been analyzed in terms of relaxation in the ground and first excited torsional states. The results are based on a population analysis of the density of states for the two cases.