Electronic structure of the oxides of lead. Part 1.—A study using X-ray and ultraviolet photoelectron spectroscopy of the oxidation of polycrystalline lead
HeI and HeII spectra of clean polycrystalline lead are reported and discussed. The oxidation of this polycrystalline lead foil by both ground-state molecular and microwave-excited oxygen has been studied using UPS and XPS techniques in combination in the same apparatus. Work function changes were also measured. The initial process is deduced to be dissociative adsorption of oxygen leading to a lead-rich surface oxide, which then oxidises more slowly with continued exposure to form rhombic PbO : the production of PbO at the surface is shown to take much longer than was hitherto thought necessary. Correlation of the valence and core-electron spectra indicates that UPS escape depths are much smaller than those for XPS, being about two atomic layers only in the present system.