title: Transition from atomic to molecular adsorption of oxygen on tungsten monomer anion.
abstract: Using vibrationally resolved ultraviolet photoelectron spectroscopy, we studied oxygen adsorption on W monomer anions. Three oxygen atoms are atomically bound in a WO3- compound, whereas in WO4- the fourth oxygen atom is attached to the oxygen, forming a di-oxygen species, implying that atom to molecule transition of O2 takes place when the number of oxygen atoms attached to a W monomer anion exceeds three. Our results indicate that molecular adsorption of oxygen is preferred on electron-deficient metals, showing that the driving force of the atom to molecule transition for the chemisorption of diatomic molecules can be the variations of electronic structures of metal hosts.
authors.affiliation: Department of Physics, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: Davor
authors.initials: D
authors.lastname: Stolcic
authors.forename: Young Dok
authors.initials: YD
authors.lastname: Kim
authors.forename: Gerd
authors.initials: G
authors.lastname: Ganteför