Nondissociative Adsorption of O2on Ge(100)

Abstract

Surface scattering experiments indicate that the dissociative chemisorption of O2 on Ge(100) and Si(100) both proceed through precursor mediate mechanisms. The theoretical studies of O2/Ge(100), unlike those of O2/Si(100) that are extensive and comprehensive, have not yet been able to account for such experimental data because of the omission of the unusual triplet spin nature of the ground state of O2. In this work we have tracked by first principles calculations the reaction paths of both triplet and singlet O2/Ge(100) and identified several nondissociative chemisorption states that “mediate” the subsequent dissociative chemisorption of ground state O2. In addition to explaining the experimentally observed precursor mediate routes, our computational comparison of O2/Ge(100) and O2/Si(100) also predicts, consistent with known experimental data, a smaller sticking coefficient for O2/Ge(100).