Scattering of N2 molecules from tungsten surfaces: crystallographic anisotropy effects in the energy exchanges

Elastic and inelastic scattering of nitrogen molecules from tungsten surfaces is studied to understand how crystallographic anisotropy affects the dynamics of fundamental elementary processes involving energy exchange during the collisions that occur under a variety of conditions of applied interest. Gaseous nitrogen molecules, in well-defined low-lying roto-vibrational states and at low-medium collision energies, impinge on two different crystallographic planes of the W surface: (100) and (110). A recently proposed Potential Energy Surface, which accurately accounts for the long-range non-covalent interactions promoting physisorption, has been used in the simulations. It has been found that reflection from the two surface orientations occurs through both direct and indirect mechanisms, with the latter being dominant at low collision energies. The vibrational state of the molecules is preserved after interacting with the gas surface, while significant anisotropy is observed in the behavior of the rotational distributions of the scattered molecules. 1.