Nondissociative adsorption of O₂ on ge(100)

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 O ₂/Ge(100).