SENSITIVITY OF ELECTRON-STIMULATED DESORPTION TO SURFACE OXYGEN ON RH(111) AND PT(111)

Surface oxygen on Rh(111) and Pt(111)has been investigated using Auger electron spectroscopy, X-ray photoelectron spectroscopy and electron stimulated desorption (ESD). Pt(111) surfaces have been investigated w ith temperature programmed desorption as well. ESD kinetic energy dist ributions (KEDs) for positive and negative ions indicate the presence of multiple bonding states for oxygen on both surfaces. ESD KEDs from surfaces judged clean with AES and XPS show the persistence of one oxy gen state after cleaning. This ESD peak remains after repeated high te mperature anneals, suggesting that it arises from oxygen bonded to imp urities or as near-surface metal oxides. This persistent signal makes ESD a much more sensitive probe for this low-coverage oxygen state on the Rh(111) and Pt(111) surfaces than common surface spectroscopies su ch as AES and XPS.