title: Two-photon photoemission study of the coverage-dependent electronic structure of chemisorbed alkali atoms on a Ag(111) surface.
abstract: We report a systematic investigation of the electronic structure of chemisorbed alkali atoms (Li-Cs) on a Ag(111) surface by two-photon photoemission spectroscopy. Angle-resolved two-photon photoemission spectra are obtained for 0-0.1 monolayer coverage of alkali atoms. The interfacial electronic structure as a function of periodic properties and the coverage of alkali atoms is observed and interpreted assuming ionic adsorbate/substrate interaction. The energy of the alkali atom σ-resonance at the limit of zero coverage is primarily determined by the image charge interaction, whereas at finite alkali atom coverages, it follows the formation of a dipolar surface field. The coverage- and angle-dependent two-photon photoemission spectra provide information on the photoinduced charge-transfer excitation of adsorbates on metal surfaces. This work complements the previous work on alkali/Cu(111) chemisorption [Phys. Rev. B 2008, 78, 085419].
authors.affiliation: Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Lei-Ming
authors.initials: LM
authors.lastname: Wang
authors.forename: Vahit
authors.initials: V
authors.lastname: Sametoglu
authors.forename: Aimo
authors.initials: A
authors.lastname: Winkelmann
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Petek