MOLECULAR-LEVEL INVESTIGATIONS OF DIFFERENT TYPES OF COADSORPTION AT AG ELECTRODES BY RAMAN-SPECTROSCOPY

Five correlated adsorption and coadsorption systems, including SCN-coa dsorbed with pyridine, thiourea, and water molecules at silver electro des respectively, have been investigated by using surface enhanced Ram an spectroscopy (SERS) combined with electrochemical and quantum chemi cal methods. The coadsorption can be classified into two types - paral lel (competitive) and induced coadsorption, By anaiyzing the frequency dependences of the SERS bands from the induced coadsorbates on the el ectrode potential, one can further classify the induced coadsorption i nto two subtypes - induced physical coadsorption and induced chemical coadsorption.