The adsorption of ethene on clean and chlorine-precovered Ag(100)

RAIRS, in conjunction with LEED and electron spectroscopies, has been used to characterise both the low-temperature adsorption of ethene on the Ag(100) surface and the influence of preadsorbed chlorine on this adsorption. On the clean surface, ethene is found to be weakly τ-bonded at all coverages with dynamic pressures being required to saturate the monolayer adsorption state at 100 K. At low coverages, the molecule lies parallel to the surface plane, but further adsorption induces a reorientation involving rotation about the CC axis. The influence of preadsorbed chlorine depends critically on the Cl coverage. At low coverage values adsorption is enhanced and LEED shows the presence of ordered ethene-chlorine structures, although no substantial re-hybridisation of the ethene is induced. At high Cl coverage a progressive passivation of the surface is produced.