Another significant finding arising from this work is that the dissociative chemisorption probability of CO 2 on Cu(110) is largely independent of the incidence angle and follows total energy scaling, rather than normal energy scaling (Figure ). In many cases of moleculesurface collisions, where the interaction PES exhibits low corrugation, the parallel component of the incident momentum does not get exchanged and largely behaves like a spectator mode. This leads to the so called normal energy scaling, where the S 0 solely depends on E n (and not on E i ). On the other hand, if the molecule-surface interaction potential is corrugated or is highly anisotropic, then a significant exchange among the perpendicular and parallel components of incident momenta can occur, ultimately leading to deviation from normal energy scaling. Similar characteristics have been reported previously for the physisorption dynamics of CO 2 on Cu(110), 5 studied up to an E i of 1.3 eV. Here too the physisorption probability was reported to follow total energy scaling. Since we have measured CO 2 dissociation probability at much higher incident energies, it is reasonable to conclude that the incident molecules penetrate the surface electron density sufficiently and encounter a significant amount of corrugation. This combined with the anisotropic nature of the PES can give rise to the total energy scaling behavior, as observed in the present case. Further experiments, especially looking into the inelastic scattering and energy transfer, are likely to shed more light on this aspect. In particular, broadening of the angular distribution as a function of incident energy caused by large corrugation is expected.