Vibrational relaxation of NO on Au(111) via electron-hole pair generation

Abstract

Recent experiments have demonstrated the breakdown of the Born-Oppenheimer approximation when NO undergoes inelastic scattering from a Au(111) surface. In this paper, we provide a simple theoretical model for understanding this phenomenon. Our model predicts multiquanta vibrational relaxation through the creation of high-energy electron-hole pair excitations in the metal. Using experimentally determined parameters, our model gives qualitatively accurate predictions for the final vibrational state populations of the scattered molecule and predicts efficient conversion of vibrational energy into electronic energy.

On the temperature dependence of electronically non-adiabatic vibrational energy transfer in molecule–surface collisions

“…As the temperature of the surface becomes larger, the Arrhenius behavior breaks down, and the linear temperature dependence takes over, according to approximation (13b). The pre-exponent of this Arrhenius form, as essentially given by the numerator of (12), is almost independent of the temperature of the surface, and its dependence on the interaction time is shown in Fig. 5.…”

“…This leads to eqn (12), which gives the absolute vibrational excitation probability P vv 0 as a function of the interaction time t and surface temperature T S :…”

“…Fig. 6 and 7 illustrate the approach to thermal equilibrium where the exact solutions, eqn (12), are plotted as a function of the interaction time and surface temperature, respectively, approaching the maximum possible value of 1 2 given by (13d). It is thus clear that the Arrhenius surface temperature dependence of the single-quantum vibrational excitation probability observed experimentally 1,[17][18][19] can be reproduced by a kinetic model (9)-(10) with the analytical expression (5) for the rate of electronically mediated vibrational energy transfer introduced in this work.…”

“…[2][3][4] Electronically mediated singlequantum vibrational energy transfer (and, more generally, the underlying molecule-surface charge transfer) was also a subject of significant theoretical effort. [5][6][7][8][9][10][11][12][13][14][15][16] In a recent paper 17 we reported observations of electronically non-adiabatic multi-quantum vibrational excitation in NO collisions with Au(111), where absolute vibrational excitation probabilities of NO(v = 0 -1, 2) were measured as a function of surface temperature, and a state-to-state kinetic model was introduced to help interpret the experimental data. That model assumed the rates of the energy transfer k vv 0 to be proportional to the number of excited electron-hole pairs whose excitation energy matches the vibrational spacing of the molecule, leading to expressions of the following type:…”

Vibrational deexcitation and rotational excitation of H2 and D2 scattered from Cu(111): Adiabatic versus non-adiabatic dynamics

“…also expected in the interaction of surfaces with initially vibrationally excited molecules. Thus, Shenvi et al 12,13 have been able to explain the observed multi-quantum vibrational relaxation of NO scattered from Au(111) using a model that incorporates electron hopping between the surface and the molecule. More recently, low dimensional calculations performed by Monturet et al 14 suggest that an electronic friction model may also account for many of the results obtained in this kind of experiment.…”