A comparison between the oxidation of bulk lead and that of lead deposits on Au(111): An auger study

Abstract

A comparison of the oxidation of bulk lead with the oxidation of thin lead layers on an inert gold substrate provides important information on both processes, particularly on the transition from surface to bulk oxidation. The exposure to oxygen of bulk polycrystalline lead at room temperature rapidly produces an oxide layer which grows laterally as a film 2.0 ± 0.2 monolayers thick, followed by much slower oxygen uptake. The same oxide, PbO, forms for lead films of submonolayer to several monolayers thickness, deposited on a Au(111) surface. For lead deposits of less than one monolayer, the oxide grows with a thickness of one monolayer.Computer decomposition of the lead signal into metal and oxide components has been carried out using the Auger lineshapes for unoxidized metal and thick oxide as basis functions. This method provides chemical information similar to that obtained from X-ray photoelectron spectroscopy.

Superconducting Pb as material for coplanar waveguide resonators on GaAs substrates

“…When exposed to air, bulk Pb forms a thin oxide layer which passivates it against further oxidation [17]. The surface irregularities due to thermal cycling nevertheless induce concern over the long-term stability of the film, as corrosion may, e.g., start at crystallites or rifts favored by their presence.…”

Ultrathin films of lead oxide on gold: Dependence of stoichiometry, stability and thickness on O2 pressure and annealing temperature

“…1, are shown both at the deposition temperature and after an anneal of about 30 min at 120°C. During deposition, the intensity of the Pb 94-eV Auger signal increases linearly until a relatively sharp knee is reached at the completion of the first monolayer, followed by a plateau, as seen previously [7,8,13,14] for deposition with the Au substrate at room temperature, although some of these results show evidence of a second knee before the plateau. The inverse behavior occurs with the Au 71-eV Auger signal.…”

“…There was no evidence of oxygen adsorption by clean Au surfaces on exposure to O 2 near room temperature up to 10 À3 Torr, either in AES or with the HS-QCM, as noted previously [14]. However, in some experiments a weak O(KVV) AES signal, equivalent to roughly 0.05 MLE of atomic oxygen, was recorded after Ar cleaning.…”

“…In all cases, the lead films are reported to oxidize to orthorhombic (yellow) PbO, as observed by X-ray diffraction for oxide films on bulk lead [15]. Moreover, earlier work [14] has shown that the oxidation kinetics for a thin film of Pb on a Au substrate are almost identical to that for bulk Pb.…”

“…[7][8][9][10]) and there exist a number of studies of oxidation by gaseous oxygen of both Pb deposited on a wide range of substrates under varying conditions (for example [11][12][13][14] and references cited therein), and bulk Pb [15]. In all cases, the lead films are reported to oxidize to orthorhombic (yellow) PbO, as observed by X-ray diffraction for oxide films on bulk lead [15].…”