Measurement of phonon densities of states for pure and hydrogenated amorphous silicon

Vibrational spectra for a-Si and a-SiH/sub 0.12/ have been measured by inelastic neutron scattering, directly yielding the phonon density of states for the former material, and the partial phonon density of states for H vibrations for the latter. The relevance of these results to the interpretation of infrared and Raman spectra is discussed.