SURFACE-ENHANCED RAMAN-SPECTROSCOPIC STUDY OF IMIDAZOLIDINE-2-THIONE ADSORBED ON SILVER ELECTRODES

Surface-enhanced Raman (SER) spectra have been obtained from imidazoli dine-2-thione (or N,N'-ethylenethiourea, ETU) adsorbed on Ag electrode s in different electrolyte solutions with different pH's. A decrease i n the frequencies in the nu(C=S) vibrational modes by 10 to 20 cm-1 an d in the nu(N-H) vibrational modes by about 115 cm-1 from the free mol ecule are observed. Vibrational analysis of the SER spectra of ETU is made in comparison to the bulk-phase Raman spectrum of ETU, and the in frared data on its metal complexes. It is concluded that the ETU molec ules are bonded undissociatively to the Ag surfaces through their S as well as N atoms.