Experiments, for the electron stimulated desorption of CO molecules from Ru(0001) [Wurm , Phys. Rev. Lett. 74, 2591 (1995)] are rationalized with the help of quantum wave packet methods using a bimodal two-state model. Besides a vibrational population inversion for the desorbing molecule we also find a small amount of dissociation, and an experimentally observed positive correlation between vibrational state and kinetic energy of the desorbing molecules. The role of vibrational excitation of the initial state is discussed. Classical trajectory calculations are found to be in good agreement with quantum dynamics thus allowing for a systematic exploration of the sensitivity of the results on details of the potential energy surfaces.