XPS and ab initio study of the interaction of PbTe with molecular oxygen

Density functional (B3LYP) calculations have been performed to investigate the adsorption of O 2 ( 3 Σ g - ) molecule on the surface of cluster (PbTe)4. To study the influence of point defects (namely, impurity atoms and cation and anion vacancies) on the reactivity of PbTe surface, clusters (PbTe)3GeTe, (PbTe)3GaTe, (PbTe)3Te, and (PbTe)3(Pb) were investigated. The adsorption of oxygen on the surface of (PbS)4 cluster was calculated to evaluate the role of anions in the adsorption process. It was shown that the formation of the peroxide-like complex is the first step of adsorption. The calculated tendency to surface oxidation increases in sequence: PbTe with cation vacancies <PbS < pure PbTe < PbTe doped with Ga < PbTe doped with Ge < PbTe with anion vacancies. The results of quantum-chemical calculations correlate with X-ray photoelectron spectroscopy data.