Disentangling the Role of Electrons and Phonons in the Photoinduced CO Desorption and CO Oxidation on (O,CO)-Ru(0001)

TL;DR

This study investigates how electronic and phononic excitations influence femtosecond laser-induced CO desorption and oxidation on Ru(0001), revealing phonons primarily govern desorption and likely oxidation.

Contribution

It provides the first ab initio molecular dynamics analysis distinguishing the roles of electrons and phonons in these surface reactions.

Findings

CO desorption is primarily driven by phononic excitations.

Phononic excitations and surface distortions are important in oxidation.

Electronic excitations alone are insufficient to explain the reactions.

Abstract

The role played by electronic and phononic excitations in the femtosecond laser induced desorption and oxidation of CO coadsorbed with O on Ru(0001) is investigated using ab initio molecular dynamics with electronic friction. To this aim, simulations that account for both kind of excitations and that only consider electronic excitations are performed. Results for three different surface coverages are obtained. We unequivocally demonstrate that CO desorption is governed by phononic excitations. In the case of oxidation the low statistics does not allow to give a categorical answer. However, the analysis of the adsorbates kinetic energy gain and displacements strongly suggest that phononic excitations and surface distortion also play an important role in the oxidation process.