title: Electron-hole pair excitation determines the mechanism of hydrogen atom adsorption.
abstract: How much translational energy atoms and molecules lose in collisions at surfaces determines whether they adsorb or scatter. The fact that hydrogen (H) atoms stick to metal surfaces poses a basic question. Momentum and energy conservation demands that the light H atom cannot efficiently transfer its energy to the heavier atoms of the solid in a binary collision. How then do H atoms efficiently stick to metal surfaces? We show through experiments that H-atom collisions at an insulating surface (an adsorbed xenon layer on a gold single-crystal surface) are indeed nearly elastic, following the predictions of energy and momentum conservation. In contrast, H-atom collisions with the bare gold surface exhibit a large loss of translational energy that can be reproduced by an atomic-level simulation describing electron-hole pair excitation.
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany. International Center for Advanced Studies of Energy Conversion, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. oliver.buenermann@chemie.uni-goettingen.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bünermann
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Dorenkamp
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kandratsenka
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Svenja M
authors.initials: SM
authors.lastname: Janke
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Auerbach
authors.affiliation: Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany. Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany. International Center for Advanced Studies of Energy Conversion, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.
authors.forename: Alec M
authors.initials: AM
authors.lastname: Wodtke