Inelastic Neutron Scattering from Amorphous Germanium

Abstract

Inelastic neutron scattering has been used to study vibrational spectra of amorphous germanium. For large momentum transfers, i.e. several times that of the first maximum in the amorphous x‐ray scattering pattern, neutron energy loss spectra should become insensitive to further changes in momentum transfer and are then simply related to the vibrational density of states. This incoherent limit neutron scattering method in principle avoids the matrix element uncertainties which enter interpretations of infrared absorption and Raman scattering experiments. Preliminary results, obtained with a 5 gram sample of evaporated amorphous germanium, indicate that the lowest energy peak in the density of states is broadened, and its center of gravity is shifted to somewhat lower energy than the corresponding TA phonon peak in the crystalline density of states.