Absence of isotope effects in the photo-induced desorption of CO from saturated Pd(111) at high laser fluence

Abstract

Neural network-based potential energy surfaces are currently gaining relevance in the context of gas-solid dynamics. In this work, we use this methodology to theoretically explore femtosecond laser pulse induced desorption of CO from the Pd(111) surface with a coverage of 0.75 ML. We performed molecular dynamics simulations in the high laser fluence regime on two different CO isotopes, 12C16O and 13C18O, in order to search for possible isotope effects affecting the photo-induced desorption. According to our findings, isotope effects of relevance do not appear in desorption probabilities once the whole process has finished after 50 ps. However, for those molecules desorbed with the highest translational kinetic energies, we obtain that 12C16O molecules are more vibrationally excited than 13C18O. This mostly happens as a consequence of the interaction of adsorbed CO with the laser-excited electrons in the substrate.