AVS 50th International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThA

Paper AS-ThA10
Surface Vibrational Spectroscopy Beyond the Harmonic Approximation: On the Selection Rules of Binary Modes

Thursday, November 6, 2003, 5:00 pm, Room 324/325

Session: Electron and Photon Spectroscopies
Presenter: P.E: Uvdal, Lund University, Sweden
Authors: P.E: Uvdal, Lund University, Sweden
M. Andersson, Lund University, Sweden
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Vibrational analysis of surface adsorbates involves in general the assignment of fundamental normal modes. Based on such assignment conclusions about chemical identity and geometry can be drawn. It is however well known from fundamental textbooks on molecular vibrations that if one goes beyond the harmonic approximation of the intramolecular bond potential overtone and combination modes are allowed. Binary modes, i.e. excitation of one vibration with two quanta or excitation of two vibrations with one quanta, will be the most intense even though higher excitations are allowed. The presence or absence of binary modes will contain information about bond anharmonicity and coupling between different modes. The selection rules, that is the absesence/presence of them will be descussed based on recent first principle calculations.@footnote 1@ @FootnoteText@ @footnote 1@M.P. Andersson and P. Uvdal, Phys. Rev. Lett. 90 (2003) 076103.