Interactions of fast N-2 molecules with palladium surfaces

Time-of-flight measurements of N-2 and N-2(+) scattered off clean and potassium covered Pd-surfaces indicate a collisional dissociation mechanism for kinetic energies of 250 up to 5000 eV and grazing incidence (5 degrees). Therefore, this system is predestined to be described within the framework of Newton's mechanics. Classical trajectory calculations have been carried out using different types of interaction potentials. It turned out that results from simulations based on pair potentials are not in full agreement with the experimental data, so we performed additional calculations using semi-empirical potential energy surfaces, The importance of dissociation due to rotational and vibrational excitation respectively depends strongly on the initial molecular axis orientation as well as on the crystallographic azimuthal direction.