Energy dissipation channels in hyperthermal atomic and molecular scattering off metal surfaces

L. MARTIN-GONDRE; G.A. BOCAN; J.I. JUARISTI; M. ALDUCIN; R. DÍEZ MUIÑO

Groningen

Conferencia; XXVII European Conference on Surface Science; 2010

ECOSS

Dynamics   of   hyperthermal   atoms   and   molecules   scattered   off   metal   surfaces   can   be significantly affected by the excitation of phonons and electron­hole pairs. We evaluate the role of both energy dissipation channels in the non­reactive scattering of N atoms at Ag(111) surfaces   and   N2  molecules   at   W(110)   surfaces.   Our   calculations   are   based   on   potential energy surfaces accounting for the full dimensionality of the problem and built from density functional theory data. The non­reactive probabilities  are derived from classical dynamics using a conventional Monte Carlo sampling of all possible initial conditions. Electron­hole pair excitations   are   included   using   a   local   friction   coefficient   [1].   The   phonon   contribution   is obtained in the Generalized Langevin Oscillator Model. The theoretical results thus obtained agree reasonably well with existing experimental data [2,3]. We show that phonon excitations are much more efficient than electron excitations in dissipating the incident kinetic energy. However,   both   channels   are   intimately   entangled   and   the   total   energy   transferred   to   the surface cannot be evaluated as a sum of two independent channels. References[1] JI Juaristi, M Alducin, R Díez Muiño, HF Busnengo and A Salin 2008  Phys. Rev. Lett.      100 116102[2] TF Hanisco and AC Kummel, 1993 J. Vac. Sci. Technol. A 11, 1907[3] H Ueta, MA Gleeson, and AW Kleyn 2009 J. of Phys. Chem. A 113 15092