We have studied the effect of deuteration on the adsorption of benzoic
acid on a copper (110) surface with RAIRS and HREELS. The resulting b
enzoate species has been characterized by the assignment of the spectr
a to modes of A1 symmetry under the C2v point group, which shows the c
arboxylate group and aromatic ring are perpendicular to the surface. C
omparison to the non-deuterated species shows some unexpectedly large
intensity changes and frequency shifts for several aromatic ring breat
hing modes due to coupling with modes of the carboxylate group.