title: Evidences of alkali-induced softening of the oxygen-substrate bond.
abstract: The interaction of oxygen with alkalis (Na, K) on Ni(111) was studied by high-resolution electron energy loss spectroscopy. Loss measurements revealed for the first time a softening of the O-Ni bond and, simultaneously, a strengthening of the alkali-Ni bond in the alkali+O coadsorbed phase, in perfect agreement with recent theoretical calculations. The weakening of the O-Ni bond was ascribed to the alkali-induced filling of the O 2p(z) antibonding orbitals. Different physical mechanisms were discussed for explaining the strengthening of the alkali-substrate bond whenever alkalis are coadsorbed with O adatoms.
authors.affiliation: Dipartimento di Fisica and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM), Università degli Studi della Calabria, Rende(Cs), Italy.
authors.forename: A
authors.initials: A
authors.lastname: Politano
authors.forename: V
authors.initials: V
authors.lastname: Formoso
authors.forename: R G
authors.initials: RG
authors.lastname: Agostino
authors.forename: E
authors.initials: E
authors.lastname: Colavita
authors.forename: G
authors.initials: G
authors.lastname: Chiarello