Competition between the electron- and phonon-excitation channels in atomic and molecular scattering off metal surfaces

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

Asis

Conferencia; Molecular Reaction Dynamics in Gases, Liquids and Interfaces (Faraday Discussion 157); 2012

<!-- @page { margin: 0.79in } P { margin-bottom: 0.08in; direction: ltr; color: #000000; widows: 2; orphans: 2 } P.western { font-family: "Times", serif; font-size: 11pt; so-language: en-GB } P.cjk { font-family: "Times New Roman", serif; font-size: 11pt } P.ctl { font-family: "Times", serif; font-size: 10pt; so-language: ar-SA } A.sdfootnotesym-western { font-family: "Times New Roman", serif; font-size: 11pt } A.sdfootnotesym-cjk { font-size: 11pt } A.sdfootnotesym-ctl { font-family: "Times New Roman", serif; font-size: 11pt } --> Dynamics of hyperthermal atoms and molecules scattered off metal surfaces can be significantly affected by the excitation of phonons and electron-hole pairs. We evaluate the role of both energy dissipation channels in the non-reactive scattering of Nitrogen atomic and molecular species off Ag and W 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 non-reactive probabilities are derived from classical dynamics using a conventional Monte Carlo sampling of all possible initial conditions. Electron-hole 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. We also show that, even when the energy dissipated is quantitatively significant, important aspects of the scattering dynamics are well captured by the adiabatic approximation. <!-- @page { margin: 0.79in } P { margin-bottom: 0.08in; direction: ltr; color: #000000; widows: 2; orphans: 2 } P.western { font-family: "Times", serif; font-size: 11pt; so-language: en-GB } P.cjk { font-family: "Times New Roman", serif; font-size: 11pt } P.ctl { font-family: "Times", serif; font-size: 10pt; so-language: ar-SA } A.sdfootnotesym-western { font-family: "Times New Roman", serif; font-size: 11pt } A.sdfootnotesym-cjk { font-size: 11pt } A.sdfootnotesym-ctl { font-family: "Times New Roman", serif; font-size: 11pt } --> 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