Translational Energy Selection of Molecular Precursors to Oxygen Adsorption on Pt(111)

Adsorption intermediates of oxygen on a platinum (111) surface were examined with electron energy-loss spectroscopy (EELS) and molecular beams. Low incident kinetic energies promote initial adsorption into both a superoxolike $\left(870\mathrm{cm}{}^{-1\mathrm{}}\right)$ and peroxolike $\left(690\mathrm{cm}{}^{-1\mathrm{}}\right)$ molecular surface species at 77 K. High incident energies, however, exclusively populate the more strongly bound peroxolike species, suggesting a close correlation between incident kinetic energy and the reaction coordinate for adsorption. This investigation directly verifies surface intermediates in high kinetic energy adsorption and provides evidence of translational energy affecting adsorption product distribution.