ATOMISTIC STUDIES OF O-2 DISSOCIATION ON PT(111) INDUCED BY PHOTONS, ELECTRONS, AND BY HEATING

The adsorption and subsequent dissociation of O-2 on Pt(111) was studi ed by variable temperature scanning tunneling microscopy in the temper ature range of 40 to 215 K. Tight clustering of bridge site molecules is observed on terraces between 40 and 70 K, indicating a highly mobil e precursor to chemisorption. Coexistence of bridge and fee hollow sit e molecules in fractal-shaped islands is observed after dosing between 70 and 95 K. Dissociation of these species was induced by uv radiatio n, inelastic tunneling electrons, and heating. In all three cases, two O atoms are found within two lattice constants of the original molecu le and one to three lattice constants apart. (C) 1997 American Institu te of Physics.