The formation of subsurface oxygen on Pt{110} (1x2) from molecular-beam-generated O-2 (1)Delta(g)

An unusually high-peak-temperature desorption state of O-2 from Pt{110} (1x 2) has been characterized in temperature programmed desorption spectra afte r O-2 adsorption from a supersonic beam at a translational energy of 190 me V and at nozzle temperatures, T-n, greater than 870 K. It shows the charact eristics of a subsurface atomic state of oxygen. From the nozzle temperatur e dependence of the rate of population of this state we conclude that it is formed exclusively from electronically excited O-2 (1)Delta(g) generated i n the molecular beam source. (C) 2000 American Institute of Physics. [S0021 - 9606(00)70518-6].