Anharmonic resonances in the C–H stretch region of ethoxy adsorbed on W(1 1 0): vibrational spectroscopy and calculations

We show that it is possible to understand and interpret the complex and rich C–H stretch region in the vibrational spectrum of ethoxy adsorbed on W(1 1 0) in terms of fundamental C–H stretch modes in Fermi resonance with C–H deformation overtones and combinations. The mode assignment is based on calculated 13C isotopic shifts for an ethoxy-Cu5 cluster. The coupling constants have been derived from calculated energy third derivatives of free ethanol and the coupling was implemented by an effective Hamiltonian matrix. The agreement with experiments is very good.