portrait portrait

The 15th International Conference on

Vibrations at Surfaces

June 22-26, 2015 ▪ Donostia-San Sebastián, Spain

Donostia Igeldotik

Program

OverviewMondayTuesdayWednesdayThursdayFriday

Friday June 26

09:30-10:40 Fr1: Thermal transport, friction, and dissipation
10:40-11:20 Coffee break
11:20-13:00 Fr2: Catalysis and single-molecule chemistry
13:00-14:00 Closing session with poster prize ceremony, G. Benedek

Fr1: Thermal transport, friction, and dissipation

Chair: M. Kawai, Tokyo, Japan

09:30-10:00 D. Donadio, San Sebastián, Spain
How surfaces dictate thermal transport in low-dimensional semiconductors
10:00-10:20 P. Focquet, Grenoble, France
A classical collision model for surface friction tested by neutron scattering
10:20-10:40 P. Saalfrank, Potsdam, Germany
Cold or hot: Metal substrate electrons will always couple to adsorbate vibrations

Contributed talk

Cold or hot: Metal substrate electrons will always couple to adsorbate vibrations

P. Saalfrank1, J. I. Juaristi2, M. Alducin2, R. Díez Muiño2, G. Füchsel1,3, and G. Floß1

1Institut für Chemie, Universität Potsdam, Potsdam, Germany

2Donostia International Physics Center (DIPC), San Sebastián, Spain

3Leiden Institute of Chemistry, Leiden, The Netherlands

In recent years, a paradigm change began to take shape in experimental and theoretical surface science when it was realized that non-adiabatic effects, i.e., the coupling of electrons of a metal surface, say, to adsorbate degrees of freedom may have a decisive influence on their nuclear dynamics. In this contribution we present first-principles' based dynamical simulations and theory, demonstrating that indeed 'cold' and sometimes even more so, 'hot' electrons play a pronounced role during dynamical gas-surface encounters. In fact, non-adiabaticity seems the rule rather than the exception, certainly in the cases shown here.

In a first example, using the recently developed Ab Initio Molecular Dynamics with Electronic Friction (AIMDEF) method we show that vibrational relaxation of H atoms on metal (Pb) films is entirely dominated by (cold) electron-hole pairs. Phonon motion can nevertheless have some surprising impact, and so do Quantum Size Effects (QSE) which emerge with varying layer thickness [1]. Classical or open-system density matrix dynamics and generalized electronic friction models reveal the importance of 'cold' electrons during reactive and non-reactive molecule-metal surface scattering, as will be demonstrated for H2 near Ru(0001) and NO near Ag(111) [2]. Finally, 'hot' electrons created by femtosecond laser pulses play the music during photoreactions of adsorbates (diffusion, (associative) desorption), for systems like H2:Ru(0001) and CO:Ru (0001) [3].

.Saalfrank.png

Figure 1: Example Langevin trajectory for hot-electron induced desorption of H2 from Ru(0001) [3].

[1] P. Saalfrank et al., J. Chem. Phys. 141, 234702 (2015)

[2] G. Füchsel et al., J. Phys. Chem. A 117, 8761 (2013); PRL 109, 098303 (2012); S. Monturet and P. Saalfrank, Phys. Rev. B 82, 075404 (2010)

[3] G. Füchsel et al., PCCP 12, 14082 (2010); PCCP 13, 8659 (2011); G. Floß et al., to be published