Scattering of Atomic Hydrogen Off a H-Covered W(110) Surface: Hot-Atom versus Eley-Rideal Abstraction Dynamics

PETUYA, R.; LARREGARAY, P.; CRESPOS, C.; AUREL, P.; BUSNEGO, H.F.; MARTINEZ, A.E.

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 119 p. 3171 - 3179

1932-7447

Normal incidence scattering of hydrogen atoms over an H-covered tungsten W(110) surface is simulated via quasiclassical trajectories. ADensity Functional Theory (DFT) based multiadsorbate potential is developed in order to model a wide range of surface coverages, 0.25 to 1 ML, reproducing the surface arrangements of adsorbates experimentally observed at low temperature. The competition between Hot-Atom (HA) and Eley-Rideal (ER) abstraction mechanisms is studied over the Ep =0.1-5.0 eV (Ep=0.1-2.0 eV) collision energy range for 0.25 ML (0.5, 0.75 and 1 ML) coverage. Cross sections, final energies of the recombination products and reaction times areanalyzed. At low coverage and low collision energy, HA dominates abstraction, whereas both processes become similar when collisionenergy increases. The vibrational distribution of recombined H2 molecules at finite coverage is found in better agreement with experiments that the one computed within the single adsorbate limit. At high surface coverage, ER dominates abstraction but the dynamical observables highlight the similarity between both reaction mechanisms thus suggesting that abstraction may be considered as a unique process.