Hot electron mediated desorption rates calculated from excited state potential energy surfaces

TL;DR

This paper develops a model for electron-induced molecular desorption on metal surfaces using excited state potential energy surfaces from DFT, highlighting the importance of molecular vibrational modes in energy transfer.

Contribution

It introduces a simple Hamiltonian model based on excited state PES that accurately describes desorption dynamics and reproduces experimental power law behaviors.

Findings

Classical nuclear dynamics is insufficient for excited state propagation.

The internal molecular stretch mode is crucial for energy transfer.

The model successfully reproduces experimental desorption power laws.

Abstract

We present a model for Desorption Induce by (Multiple) Electronic Transitions (DIET/DIMET) based on potential energy surfaces calculated with the Delta Self-Consistent Field extension of Density Functional Theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various transition metal surfaces, and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system, with parameters obtained from the excited state potential energy surface, and show that this model can describe desorption dynamics in both the DIET and DIMET regime, and reproduce the power law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong.