The Vibrational Fine Structure of Chemisorbed C2H4Molecules in the (1s-1, π*) State

Abstract
The fine structure of C2H4 molecules in the (1s-1, π*) state is resolved using a plane grating ellipsoidal mirror grazing incidence monochromator at the storage ring BESSY. Two vibrational series can be identified, assigned to C-C and C-H vibrations. The natural line width of the (1s-1, π*) state was found to be 160 meV for condensed C2H4 multilayers. For submonolayers of C2H4 molecules on Ag(100) and Cu(100) this value was found to increase to 280 and 700 meV respectively. A shift to lower energies of the ground state transition is observed for the adsorbed molecules with respect to the multilayer case.