title: Observation of direct vibrational excitation in gas-surface collisions of CO with Au(111): a new model system for surface dynamics.
abstract: We report vibrational excitation of CO from its ground (v = 0) to first excited (v = 1) vibrational state in collision with Au(111) at an incidence energy of translation of E(I) = 0.45 eV. Unlike past work, we can exclude an excitation mechanism involving temporary adsorption on the surface followed by thermalization and desorption. The angular distributions of the scattered CO molecules are narrow, consistent with direct scattering occurring on a sub-ps time scale. The absolute excitation probabilities are about 3% of those expected from thermal accommodation. The surface temperature dependence of excitation, which was measured between 373 and 973 K, is Arrhenius-like with an activation energy equal to the energy required for vibrational excitation. Our measurements are consistent with a vibrational excitation mechanism involving coupling of thermally excited electron-hole pairs of the solid to CO vibration.
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Göttingen, Germany. tschaef4@gwdg.de
authors.forename: Tim
authors.initials: T
authors.lastname: Schäfer
authors.forename: Nils
authors.initials: N
authors.lastname: Bartels
authors.forename: Kai
authors.initials: K
authors.lastname: Golibrzuch
authors.forename: Christof
authors.initials: C
authors.lastname: Bartels
authors.forename: Hansjochen
authors.initials: H
authors.lastname: Köckert
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Auerbach
authors.forename: Theofanis N
authors.initials: TN
authors.lastname: Kitsopoulos
authors.forename: Alec M
authors.initials: AM
authors.lastname: Wodtke
mesh_terms: D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D014732:Vibration
chemical_list: D005740:Gases; D006046:Gold; D002248:Carbon Monoxide