ADSORBATE-SUBSTRATE RESONANT INTERACTIONS OBSERVED FOR CO ON CU(100) IN THE FAR INFRARED

Surface infrared reflection-absorption measurements for CO adsorbed on Cu(100) in the frequency range 200-500 cm-1 reveal, in addition to the Cu-CO stretch mode at 345 cm-1, a sharp derivativelike feature at 285 cm-1, assigned to the CO frustrated rotation mode which is usually dipole forbidden. Its infrared activity and Fano line shape arise from coupling to substrate electronic transitions associated with CO-induced surface states. © 1990 The American Physical Society.