Neutron spectroscopic evidence for subsurface hydrogen in palladium

Abstract

The interaction of hydrogen with palladium black, a high-surface-area metal powder, has been investigated by incoherent inelastic neutron scattering. The vibrational spectrum associated with chemisorbed surface hydrogen occupying threefold sites has been identified. A vibrational mode at 58 meV, which is found to be inconsistent with either surface or bulk palladium-hydrogen species, is assigned to chemisorbed hydrogen occupying subsurface sites.