Nondissociative Adsorption of O2 on Ge(100)

Surface scattering experiments indicate that the dissociative chemisorption of O-2 on Ge(100) and Si(100) both proceed through precursor mediate mechanisms. The theoretical studies of O-2/Ge(100), unlike those of O-2/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 O-2. In this work we have tracked by first principles calculations the reaction paths of both triplet and singlet O-2/Ge(100) and identified several nondissociative chemisorption states that mediate the subsequent dissociative chemisorption of ground state O-2. In addition to explaining the experimentally observed precursor mediate routes, our computational comparison of O-2/Ge(100) and O-2/Si(100) also predicts, consistent with known experimental data, a smaller sticking coefficient for O-2/Ge(100).