DYNAMICS AND KINETICS OF OXYGEN DISSOCIATIVE ADSORPTION ON PT(110)(1X2)

The interaction of oxygen with Pt{110}(1X2) has been investigated usin g supersonic molecular beams and low-energy electron, diffraction (LEE D) at incident kinetic energies of 60-900 meV and surface temperatures from 170 to 1100 K. LEED studies indicate that at low exposures and l ow beam energies (<190 meV) oxygen does not induce a reconstruction to (1X1). However at high exposures and low beam energies, a variable un it mesh dimension Frenkel-Kontorova domain structure is observed. Stic king probability measurements on the clean surface indicate that oxyge n dissociative adsorption on Pt{110}(1X2) is a predominantly precursor mediated process. At low surface temperatures (<200 K) and low beam e nergies, the precursor has a strong influence on the adsorption kineti cs, and mixed. islands of dioxygen and adatoms are formed. Adsorption at beam temperatures below 880 K produces two states in the the therma l desorption spectroscopy spectra, but at higher incident gas temperat ures a new high temperature desorption state (T-p=1020 K) can be popul ated, which inhibits the formation of the usual dissociatively chemiso rbed states at T-p=720 and 820 K. (C) 1998 American Institute of Physi cs. [S0021-9606(98)70740-8].