Interaction of CO and NO with WC(0001)

The results of angular resolved photoemission and thermal desorption spectroscopy investigations of the adsorption of CO and NO on a WC(0001) single crystal surface are reported. Both molecules are stable only at low temperature. Similar to the case of adsorption on many transition metals, CO is co-ordinated to the surface via its carbon end, standing upright on the surface. Upon warming up, complete dissociation takes place at temperatures of ca 270 K for CO and 160 K for NO. A part of the CO molecules also desorbs between 200 and 250 K, whereas no molecular desorption is found for NO. Recombinative/reactive desorption is observed in the temperature range between 700 and 1200 K