Raman studies of hydrogen vibrational modes in palladium

The phonon density of states of substoichiometric polycrystalline Pd-H(D) was investigated by Raman Scattering above and below the 50 K anomaly. The Raman spectra for hydrogen and deuterium were found to be asymmetric and peaked at 58.5 meV and 39.7 meV respectively, in near agreement with inelastic neutron scattering data. The scattering mechanism appears to require hydrogen-hydrogen interactions. No major changes in the optical spectra were observed in going through the 50 K anomaly.