Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 68: Surface dynamics: Reactions, elementary processes and phase transitions I
O 68.6: Vortrag
Mittwoch, 14. März 2018, 16:15–16:30, MA 043
Electron-mediated phonon-phonon coupling drives the vibrational relaxation of molecules at metal surfaces — •Dino Novko1, Maite Alducin2,4, and Joseba Iñaki Juaristi2,3,4 — 1Freie Universität, Institut für Chemie und Biochemie, Berlin — 2Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), San Sebastián, Spain — 3Departamento de Física de Materiales, Facultad de Químicas UPV/EHU, San Sebastián, Spain — 4Donostia International Physics Center (DIPC), San Sebastián, Spain
Growing experimental evidences highlight a key role of nonadiabatic coupling in adsorbate relaxation at metal surfaces. Even though many nonadiabatic theories have emerged to comprehend these experimental endeavours, our understanding of the microscopic mechanisms that underlie the dynamical processes at metal surfaces is still incomplete. For instance, the state-of-the-art theories are still unable to give precise quantitative estimations of the experimental vibrational relaxation rates. In this contribution we propose a new relaxation process, i.e., the so-called electron-mediated phonon-phonon coupling (EMPP), that is able to elucidate the vibrational relaxation mechanism of the internal stretch mode of CO on Cu(100). In fact, we show that the EMPP process dominates over the commonly-used first-order nonadiabatic contribution. The results demonstrate a strong electron-mediated coupling between the internal stretch and low-energy CO modes, but also a significant role of the surface motion. Our nonadiabatic theory is also able to explain the temperature dependence of the internal stretch phonon linewidth, thus far considered a sign of the direct anharmonic coupling.