Abstract
The amplitude-weighted density of vibrational states for hydrogen bound by molybdenum sulphide is calculated and compared with incoherent inelastic neutron scattering data. At low coverages hydrogen bonds at the surface directly above a single sulphur atom. The intensity in the higher frequency band at approximately=350 cm-1 relative to the band at approximately=150 cm-1 is found to be increased when hydrogen is adsorbed, but the positions of these peaks do not move to higher energies. The possibility that the observed shift with increasing coverage is due to the occupancy of a multiply bonded site is considered. For this site the low-frequency band moves to higher frequencies and a resonance in the hydrogen density of states for vibrations perpendicular to the layer is found at approximately=500 cm-1 which could explain the high intensity observed at this frequency for H0.067MoS2.