Observation of a Change of Vibrational Excitation Mechanism with Surface Temperature: HCl Collisions with Au(111)

Abstract

We have measured the vibrational excitation probability (Pv) of HCl incident on a Au(111) surface at kinetic energies (Ei) of 0.59 eV to 1.37 eV and surface temperatures (Ts) of 273 K to 1073 K. For all energies, the slope of the Pv as a function of Ts exhibits a sharp increase above Ts approximately 800 K. We show this change in slope and the threshold behavior of Pv to be consistent with a change in excitation mechanism from an electronically adiabatic mechanical mechanism to an electronically nonadiabatic mechanism involving excited electron-hole pairs.

Vibrational energy transfer near a dissociative adsorption transition state: State-to-state study of HCl collisions at Au(111)

“…22 Surprisingly, those values are about 50 times smaller than the results that we report here. We attribute this discrepancy to incorrect spectroscopic assignments, resulting in erroneous detection sensitivity factors for v = 0 and 1 used in the previous work.…”

“…Using this correction factor of 50, we include the previously reported vibrational excitation probabilities from Ref. 22 in the current analysis. Fig.…”

“…145, 054709 (2016) energy transfer between HCl and the Au(111) surface proceeds by two different mechanisms: an electronically adiabatic and an electronically nonadiabatic one. 22,23 The adiabatic mechanism involves V-T coupling-as in the case of H 2 /Cu(111)-whereas the nonadiabatic mechanism requires V-EHP coupling. Accordingly, the measured excitation probabilities can be decomposed into electronically adiabatic and nonadiabatic contributions.…”

The importance of accurate adiabatic interaction potentials for the correct description of electronically nonadiabatic vibrational energy transfer: A combined experimental and theoretical study of NO(v = 3) collisions with a Au(111) surface

“…There is strong evidence for electronically nonadiabatic interaction in the collision-induced vibrational excitation of NO/Ag(111), NO/Cu(110), CO/Au(111), and HCl/Au(111). [11][12][13][14] A one-dimensional Newns-Anderson model explains the incidence-energy and surface-temperature dependence of the vibrational excitation probability for NO/Ag(111). 15 In this model, the vibrational excitation of the molecule is due to de-excitation of thermal electron-hole pairs in the metal.…”

“…For example, electronically nonadiabatic vibrational excitation probabilities for HCl(v = 0) can be less than 10 −5 . 13 Typically, simulations of rare events are computationally intensive, and molecular dynamics with IESH or EF are not exceptional. Far fewer trajectories are needed to make statistically meaningful comparison to experiment for relaxation than for excitation.…”