The surface-enhanced Raman scattering (SERS) of p-aminothiophenol adsorbed on silver measured with visible excitations is compared with the normal Raman and ultraviolet resonance Raman (UVRR) scattering of the free molecule. The SERS is dominated by four b(2) and one a(1) symmetry species of benzene ring vibrations (under an assumption of C-2v symmetry), whereas the normal Raman scattering at visible excitations only by a(1) species. The b(2) modes corresponding to the strong SERS bands are observed for the free molecule only when the electronic transition from the ground state to the lowest unoccupied molecular orbital (LUMO, pi* b(2), lambda(max) similar to 300 nm) is excited. In electrochemical environments, the b(2) SERS bands show resonance-shaped intensity profiles as a function of applied potential. The intensity-potential profiles shift to positive potentials as the excitation energy increases. This is well interpreted by a resonance Raman-like process associated with the photon-induced charge transfer from the metal to an affinity level of the adsorbed molecule. The affinity level is assigned to LUMO on the basis of the UVRR experiments and a symmetry consideration. The b(2) modes gain their intensities via a Herzberg-Teller (vibronic) term in both SERS and UVRR scattering. Due to the difference in the electronic levels vibronically coupled, however, the enhancement patterns are greatly different.