  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.

Materials Science;Chemical Physics