Observation of Optical Phonon in Palladium Hydrides Using Raman Spectroscopy

The techniques of hydrogen loading in Pd are developed by many workers. And the states of hydrogen in Pd attract many interests because they might be related to the nuclear reactions. In this study, we have tried to observe optical phonon induced by hydrogen-hydrogen interactions in Pd using Raman spectroscopy. This measurement can be done for the sample completely sealed in a glass tube cutting off the influence of the external air, because glass materials are Raman inactive. In the measurement chamber of spectroscopy device, scattered waves of the incident laser beam from the hydrogen storage Pd are detected and Raman shifts including the information about the optical phonon in the sample are derived. If the large changes in Raman spectra are found, they will help explain the nuclear effects in condensed states of palladium hydride. So far, we have not found large changes, but the peaks of Raman shift at 56 meV both for PdHx and PdDx are detected. The peaks for PdHx are consistent with the data of Sherman et al. at 58.5 meV. However, the peaks for PdDx are inconsistent with Sharman’s result at 39.7 meV.