Hot-electron-induced vibrational heating at surface: importance of a quantum-mechanical description

Vibrational heating of a surface bond by a hot electron gas is investigated with a quantum-mechanical model and its classical limit. It is shown, for a model system CO/Cu, that the quantum-mechanical description is important to correctly describe the multi-vibrational excitation at low temperature Tv, where kBTv≤ħω, the vibrational energy quantum. The subpicosecond response of the vibrational distribution is non-thermal and the probability of multiple excitations and thus reactivity predicted by the quantum model are orders of magnitude higher than that given by its classical limit.