title: Reinterpretation of the molecular O2 chemisorbate in the initial oxidation of the si(111)7 x 7 surface.
abstract: The initial oxygen adsorption on the Si(111)7 x 7 surface was investigated by high-resolution x-ray absorption spectroscopy. Below 220 K, a molecular adsorption species is identified by distinctive absorption resonances due to the 1 pi(g) molecular orbitals. The molecular species is metastabilized to have a lifetime of 15-35 min at 135 K only with the presence of atomic adsorbates of more than 0. 1 ML (monolayer). It is thus clearly evidenced that the very initial adsorption is dissociative even at 100 K and the molecular species is not a precursor state. The molecular adsorption structures with the coadsorbed oxygen atoms are suggested.
authors.affiliation: Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Matsui
authors.forename: H W
authors.initials: HW
authors.lastname: Yeom
authors.forename: K
authors.initials: K
authors.lastname: Amemiya
authors.forename: K
authors.initials: K
authors.lastname: Tono
authors.forename: T
authors.initials: T
authors.lastname: Ohta