Electronic Excitations in the Course of the Reaction of H with Coinage and Noble Metal Surfaces: A Comparison

Efficient transfer of translational energy to electron-hole pair excitation involving multiple collisions dominates H atom collisions with metal surfaces. For this reason, H atom interaction with metal surfaces cannot be modeled within the commonly used Born-Oppenheimer approximation (BOA). This fact makes H atom scattering from metal surfaces an ideal model system for dynamics that go beyond the BOA. We chose the H/Au(111) system as a model system to obtain a detailed dataset that can serve as a benchmark for theoretical models developed for describing electronically nonadiabatic processes at metal surfaces. Therefore, we investigate the influence of various experimental parameters on the energy loss in detail including isotopic variant, incidence translational energy, incidence polar and azimuthal angles, and outgoing scattering angles.

Section: Introductionmentioning

confidence: 94%

Inelastic H and D atom scattering from Au(111) as benchmark for theory

Jiang

Dorenkamp

Krüger

et al. 2019

“…Experiments on reaction of H with H adsorbed to Au observe ehp excitation, which has been attributed to the Langmuir-Hinshelwood recombination reaction. 30,31 However, by themselves these experiments give no information on the extent to which ehp excitation affects the reverse dissociative chemisorption probability, and ehp excitation is also observed in experiments on reaction of H with H adsorbed on Cu surfaces 31 although the dissociation of H 2 on Cu( 111) is described quite well with electronically adiabatic theory. 19,20,32 Calculations using ab initio molecular dynamics with electronic friction (AIMDEF) on H 2 + Pd(100) do show that the dissociation of H 2 on a metal surface can be accompanied by substantial energy dissipation to ehps, but this dissipation takes place at the product side of the barrier.…”

Section: Introductionmentioning

confidence: 95%

Dynamics of H2 dissociation on the close-packed (111) surface of the noblest metal: H2 + Au(111)

Wijzenbroek

Helstone

Meyer

et al. 2016

We have performed calculations on the dissociative chemisorption of H on un-reconstructed and reconstructed Au(111) with density functional theory, and dynamics calculations on this process on un-reconstructed Au(111). Due to a very late barrier for dissociation, H + Au(111) is a candidate H-metal system for which the dissociative chemisorption could be considerably affected by the energy transfer to electron-hole pairs. Minimum barrier geometries and potential energy surfaces were computed for six density functionals. The functionals tested yield minimum barrier heights in the range of 1.15-1.6 eV, and barriers that are even later than found for the similar H + Cu(111) system. The potential energy surfaces have been used in quasi-classical trajectory calculations of the initial (v,J) state resolved reaction probability for several vibrational states v and rotational states J of H and D. Our calculations may serve as predictions for state-resolved associative desorption experiments, from which initial state-resolved dissociative chemisorption probabilities can be extracted by invoking detailed balance. The vibrational efficacy η reported for D dissociating on un-reconstructed Au(111) (about 0.9) is similar to that found in earlier quantum dynamics calculations on H + Ag(111), but larger than found for D + Cu(111). With the two functionals tested most extensively, the reactivity of H and D exhibits an almost monotonic increase with increasing rotational quantum number J. Test calculations suggest that, for chemical accuracy (1 kcal/mol), the herringbone reconstruction of Au(111) should be modeled.

“…Part of this argument can be based on the findings of recent density functional theory (DFT) calculations, which suggest that the surface reconstruction only has a small influence on the interaction of surface adsorbed H-atoms with Au(111). 59 A further reason for studying H + Au(111) is that, like H + Cu(111), 60 H + Au(111) has been the subject of recent experiments that have measured ehp excitation in interactions of H-atoms with metal surfaces, and have made attempts to determine whether the observed ehp excitation could be attributed to ER or to associative desorption reactions. [60][61][62] Furthermore, experiments using a Schottky diode detector have detected ehp excitation in scattering of thermal H-atoms from Cu and Ag surfaces in the form of chemicurrents, 63 and such experiments have determined ehp excitation energy distributions for both thermal H-and D-atoms scattering from Ag surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…59 A further reason for studying H + Au(111) is that, like H + Cu(111), 60 H + Au(111) has been the subject of recent experiments that have measured ehp excitation in interactions of H-atoms with metal surfaces, and have made attempts to determine whether the observed ehp excitation could be attributed to ER or to associative desorption reactions. [60][61][62] Furthermore, experiments using a Schottky diode detector have detected ehp excitation in scattering of thermal H-atoms from Cu and Ag surfaces in the form of chemicurrents, 63 and such experiments have determined ehp excitation energy distributions for both thermal H-and D-atoms scattering from Ag surfaces. 64,65 Electron emission from Cu, Ag, and Au surfaces induced by hyperthermal H-and D-atoms incident in plasma beams (with energies between 15 and 200 eV) has been studied by Kovacs et al 66 Much earlier, electron-hole pair excitation induced by hyperthermal Xe and Kr atoms incident on semi-conductor surfaces had been studied experimentally by Weiss et al 67 Scattering of H-atoms from copper surfaces has been investigated with electronically adiabatic models in a number of theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111)

Kroes

Pavanello

Blanco-Rey

et al. 2014

In-plane structure and ordering at liquid sodium surfaces and interfaces from ab initio molecular dynamics J. Chem. Phys. 127, 134703 (2007); 10.1063/1.2781388Publisher's Note: "Ab initio molecular dynamics simulation of the H/InP(100)-water interface" [J. Chem. Phys. 117, 872 (2002) Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction ("EF") model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated "post" ("p") the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy loss in the range 0.2-0.3 eV due to ehp excitation, which should be possible to observe. The average non-adiabatic energy losses for non-penetrative scattering exceed the adiabatic losses to phonons by 0.9-1.0 eV. This suggests that for scattering of hyperthermal H-atoms from coinage metals the dominant energy dissipation channel should be to ehp excitation. These predictions can be tested by experiments that combine techniques for generating H-atom beams that are well resolved in translational energy and for detecting the scattered atoms with high energy-resolution. © 2014 AIP Publishing LLC.