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

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, (CO)-C-12-O-16 and (CO)-C-13-O-18, 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 (CO)-C-12-O-16 molecules are more vibrationally excited than (CO)-C-13-O-18. This mostly happens as a consequence of the interaction of adsorbed CO with the laser-excited electrons in the substrate.