SITE OCCUPATION OF CO ADSORBED ON NI(100) AT HIGH CO PRESSURES

The adsorption of CO on Ni(100) has been investigated by infrared refl ection-absorption spectroscopy in the temperature range of 85 to 300 K . At 300 K we achieved CO coverages up to 0.8 ML by applying CO pressu res up to 1 mbar. The fraction of CO molecules adsorbed at terminal an d bridge sires on Ni(100) at a fixed temperature depends strongly on t he total CO coverage. The variation of the adsorption site occupancy w ith coverage is well reproduced by a lattice-gas model which takes int o account the lateral interaction of the adsorbed molecules.