Neutron vibrational spectroscopy of hydrogen and deuterium on Raney nickel

Incoherent neutron inelastic scattering has been applied to the study of the chemisorption of hydrogen and deuterium on Raney nickel (a high surface area nickel powder). The binding sites have been identified by comparing the vibrational frequencies and intensities provided by the inelastic scattering with calculations for model structures of different geometries, force constants, and symmetries. We conclude that, on Raney nickel above 150 K, hydrogen chemisorbs predominantly in sites of threefold symmetry. The ’’best fit’’ corresponds to a Ni–H bond distance of 1.88±0.03 Å and a force constant of 0.58±0.03 mdyn/Å. In addition, we have observed lateral adsorbate interactions, deuterium isotope shifts, and temperature dependent binding sites.