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The scattering of atomic nitrogen over a N-pre-adsorbed W(100) surface is theoretically described in the case of normal incidence off a single adsorbate. Dynamical reaction mechanisms, in particular Eley-Rideal (ER) abstraction, are scrutinized in the 0.1-3.0 eV collision energy range and the influence of temperature on reactivity is considered between 300 and 1500 K. Dynamics simulations suggest that, though non-activated reaction pathways exist, the abstraction process exhibits a significant collision energy threshold (0.5 eV). Such a feature, which has not been reported so far in the literature, is the consequence of a repulsive interaction between the impinging and the pre-adsorbed nitrogens along with a strong attraction towards the tungsten atoms. Above threshold, the cross section for ER reaction is found one order of magnitude lower than the one for hot-atoms formation. The abstraction process involves the collision of the impinging atom with the surface prior to reaction but temperature effects, when modeled via a generalized Langevin oscillator model, do not affect significantly reactivity. [ABSTRACT FROM AUTHOR]

Using the classical trajectory method, the dynamics of molecular recombination of Nitrogen atoms from a Tungsten (100) surface is studied. We focus our attention on the Eley-Rideal (ER) recombination mechanism. The potential energy surface is an extended version of the periodic London-Eyring-Polanyi-Sato potential, recently developed. The dynamics is explored in a wide range of projectile energies, the main objective being to compare the behavior of the probability for ER recombination and hot-atoms (HA) formation. [ABSTRACT FROM AUTHOR]