On the assignment of fundamental, overtone, and combination vibrational modes of small organic adsorbates on metal surfaces using electronic structure calculations

COLL 141

Per Uvdal and M. P. Andersson. Chemical Physics, Department of Chemistry, Lund University, P.O. Box 124, Lund, S-221 00, Sweden
Fairly straightforward DFT and HF electronic structure calculations of model complexes are used to obtain a detailed understanding of experimental vibrational spectra of surface adsorbates. The experimental data are obtained using an FTIR spectrometer in a reflection absorption configuration. The systems studied are small organic molecules adsorbed on single crystal metal surfaces in ultra high vacuum. The calculations also allow for an analysis of binary combination and overtone modes. The interaction between fundamental C-H stretch modes and overtone/combination modes of C-H bending/deformations modes are specifically discussed as well as the relation between the adsorbate - substrate coordination and the vibrational spectrum.