Time-resolved Surface-enhanced Raman Spectroscopic studies on coadsorption of derivatives of thiourea with ClO4- at Ag electrodes

By means of Surface - enhanced Raman Spectroscopy ( SERS), Time -resolved Surface - enhanced Raman Spectroscopy (TRSERS) and potential step method, the coadsorption behavior of methyl thiourea (MTU) and 1 - allyl - 2 -thiourea (ATU) with ClO4- respectively at Ag electrodes has been studied. The SERS intensity - time profiles show that the intensities of different SERS bands have surprisingly different response rates to the potential step. The response rates of the groups of the adsorbed species which is close to the electrode surface are fast. The results also indicate that MTU is vertically adsorbed on Ag electrode surface via S atom, while ATU is adsorbed on the surface via S atom and the molecules leaned to the electrode surface.