Fermi resonance coupling in a surface adsorbate: The C-H stretch in methoxy adsorbed on Cu(100) calculations and experiments

The C-H stretch spectrum of methoxy adsorbed on Cu(100) has been measured using Fourier transform infrared spectroscopy. Fermi resonance coupling constants in methoxy are calculated using a normal mode model where the unperturbed modes were either experimentally determined or inferred from ab initio calculations performed for a methoxy-Mo model complex. The measured frequency shifts and intensity redistribution observed in the C-H stretch region are qualitatively reproduced by the calculations. (C) 2000 American Institute of Physics. [S0021- 9606(99)71348-6].