AVS 53rd International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM1
Theory of Electron-Hole Pair Excitation in Chemisorption

Wednesday, November 15, 2006, 8:00 am, Room 2004

Session: Electronic and Vibrational Excitations and Dynamics
Presenter: M.S. Mizielinski, University of Bath, UK
Authors: M.S. Mizielinski, University of Bath, UK
D.M. Bird, University of Bath, UK
M. Persson, University of Liverpool, UK
S. Holloway, University of Liverpool, UK
Correspondent: Click to Email
It has long been recognised that the excitation of electron-hole pairs is an important mechanism for the transfer of energy to a surface in the adsorption of molecules on metal surfaces. Interest in electron-hole pair excitation has been revived recently with the observation of 'chemicurrents'@footnote 1@ and exo-electron emission following vibrational de-excitation.@footnote 2@ These phenomena are fundamentally non-adiabatic processes and require a theoretical description which goes beyond the Born-Oppenheimer approximation. To do this using ab-initio time-dependent DFT is computationally very expensive. Our approach is to gain an insight into the adsorbate-surface interaction by considering a simple model system. We analyse the non-adiabaticity by solving the time-dependent, mean-field Newns-Anderson model in the wide-band limit. In our previous work@footnote 3@ we have used this model to explore the non-adiabatic behaviour of the occupation of the adsorbate energy levels and the energy transfer between adsorbate and the metal surface. We present an extension of this work to an analytic solution for the time-evolving spectrum of excited electrons and holes. We will use this model to demonstrate the evolution of the excitation spectrum for a range of model systems. @FootnoteText@ @footnote 1@ B. Gergen et al., Science 294, 2521 (2001).@footnote 2@ J. D. White et al. Nature 433, 503 (2005).@footnote 3@ M. S. Mizielinski, D. M. Bird, M. Persson and S. Holloway, J. Chem. Phys. 122, 084710 (2005).