Surface-enhanced Raman spectroscopic study of imidazolidine-2-thione adsorbed on silver electrodes

Abstract

Surface-enhanced Raman (SER) spectra have been obtained from imidazolidine-2-thione (or N,N '-ethylenethiourea, ETU) adsorbed on Ag electrodes in different electrolyte solutions with different pH's. A decrease in the frequencies in the ν(C=S) vibrational modes by 10 to 20 cm −1 and in the ν(NH) vibrational modes by about 115 cm −1 from the free molecule are observed. Vibrational analysis of the SER spectra of ETU is made in comparison to the bulk-phase Raman spectrum of ETU, and the infrared data on its metal complexes. It is concluded that the ETU molecules are bonded undissociatively to the Ag surfaces through their S as well as N atoms.