Electron-hole pairs during the adsorption dynamics of O2 on Pd(100) - Exciting or not?

Abstract

During the exothermic adsorption of molecules at solid surfaces dissipation of the released energy occurs via the excitation of electronic and phononic degrees of freedom. For metallic substrates the role of the nonadiabatic electronic excitation channel has been controversially discussed, as the absence of a band gap could favour an easy coupling to a manifold of electronhole pairs of arbitrarily low energies. We analyse this situation for the highly exothermic showcase system of molecular oxygen dissociating at Pd(100), using time-dependent perturbation theory applied to first-principles electronic-structure calculations. For a range of different trajectories of impinging O2 molecules we compute largely varying electron-hole pair spectra, which underlines the necessity to consider the high-dimensionality of the surface dynamical process when assessing the total energy loss into this dissipation channel. Despite the high Pd density of states at the Fermi level, the concomitant non-adiabatic energy losses nevertheless never exceed about 5% of the available chemisorption energy. While this supports an electronically adiabatic description of the predominant heat dissipation into the phononic system, we critically discuss the non-adiabatic excitations in the context of the O2 spin transition during the dissociation process.

20 pages including 7 figures; related publications can be found at http://www.fhi-berlin.mpg.de/th/th.html [added two references, changed V_{fsa} to V_{6D}, modified a few formulations in interpretation of spin asymmetry of eh-spectra, added missing equals sign in Eg.(2.10)]

References in corpus (10)

• Non-adiabatic Effects in the Dissociation of Oxygen Molecules at the Al(111) Surface
• Energy loss of atoms at metal surfaces due to electron-hole pair excitations: First-principles theory of "chemicurrents"
• Fingerprints for spin-selection rules in the interaction dynamics of O2 at Al(111)
• Electron-hole pair creation by atoms incident on a metal surface
• Signatures of nonadiabatic O2 dissociation at Al(111): First-principles fewest-switches study
• Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces
• Electronic damping of molecular motion at metal surfaces
• Electron-hole spectra created by adsorption on metals from density-functional theory
• Newns-Anderson model of chemicurrents in H/Cu and H/Ag
• Spectrum of electronic excitations due to the adsorption of atoms on metal surfaces

Cited by in corpus (6)

• Modeling Heat Dissipation at the Nanoscale: An Embedding Approach for Chemical Reaction Dynamics on Metal Surfaces
• Mode specific electronic friction in dissociative chemisorption on metal surfaces: H${}_2$ on Ag(111)
• Electronic friction-based vibrational lifetimes of molecular adsorbates: Beyond the independent atom approximation
• Energy Dissipation during Diffusion at Metal Surfaces: Disentangling the Role of Phonons vs. Electron-Hole Pairs
• Non-Adiabatic Vibrational Damping of Molecular Adsorbates: Insights into Electronic Friction and the Role of Electronic Coherence
• Ready, set and no action: A static perspective on potential energy surfaces commonly used in gas-surface dynamics