Direct observation of molecular hydrogen binding to magnesium oxide (1 0 0) surfaces

Abstract

Inelastic neutron scattering (INS) studies of the dynamical response of H 2 films adsorbed on MgO (1 0 0) surface are compared to and correlated with structural information from neutron diffraction measurements of equivalent D 2 films. At low coverage, a prominent peak, believed to be the para–ortho transition (usually observed at 14.7 meV in bulk H 2 ) is observed at ∼ 11.2 meV . For film thicknesses between 0.8 and ∼ 3 layers this peak becomes asymmetric with additional scattering on the high-energy transfer side of the peak. As molecules are added to the third layer we observe the concomitant growth of a peak at 14.7 meV.