Dynamics of physisorbed monolayer of methane on Ag(1 1 1)

The adsorption, desorption and vibrational excitation dynamics of methane monolayer physisorbed on a Ag(1 1 1) surface was studied by LEED and HREELS measurements. For LEED observation, electron stimulated desorption of adsorbed CH4 was obvious even at a minimized incident electron current of 1 nA, and the result suggests the possibility of leftover of electron stimulated reaction on the substrate that cannot be identified by LEED nor desorb at raised temperature. Mode dependence of the width of energy loss peak was observed in the HREEL spectra. The excitation of the vibrational mode with sharper width is mainly associated with dipole scattering mechanism.