LOW-ENERGY PATHWAY FOR THE FORMATION OF A PT(111)-N(2X2) OVERLAYER

A low energy pathway for the formation of a thermally stable pt(111)-N(2 x 2) dioxygen and ammonia are coadsorbed at Pt(111) or a Pt(111)-O overlayer is exposed to ammonia at 295 K, although in the latter case there is also evidence for incomplete dehydrogenation. Synthesis of the nitride overlayer occurs under conditions where ammonia adsorption is negligible (theta < 0.01) and dissociative chemisorption of dinitrogen is not feasible. XPS, VEELS and LEED are used to follow surface nitride formation which is driven by the overall thermodynamics of the reaction.