POTENTIAL-AVERAGED SURFACE-ENHANCED RAMAN-SPECTROSCOPY

This paper describes a novel technique called potential-averaged surfa ce-enhanced Raman spectroscopy (PASERS) which has several advantages o ver SERS. A PASERS spectrum is acquired when the electrode is rapidly modulated between two potentials by applying a square-wave voltage. Th e potential-averaged SERS spectrum contains all the information on the surface species at the two modulated potentials, and each individual SERS spectrum can then be extracted by deconvolution, By properly choo sing the two modulating potentials, one can obtain SERS spectra of sur face species at electrode potentials where SERS-active sites are norma lly unstable. PASERS also leads to a unique way of studying complex in terfacial kinetic processes by controlling the voltage pulse height, f requency, and shape. Moreover, the measurement of time-resolved spectr a in the very Low vibrational frequency region can be achieved by PASE RS with the use of a conventional scanning spectrometer with a single- channel detector, In this paper, the main advantages of PASERS are ill ustrated by studying two typical SERS systems, i.e., thiocyanate ion a nd thiourea adsorbed at silver electrodes, respectively. It is shown t hat the potential-averaging method can be applied as a common method t o many other existing spectroelectrochemical techniques.