Kinetic Features of SERS Quenching by Underpotential Deposition (UPD) of Cd and Tl on Ag Electrodes

Abstract

Abstract Surface-enhanced Raman scattering (SERS) in the Ag/pyridine system is quenched through a biphasic kinetics, after completion of submonolayer underpotential deposition (UPD) of Cd. This result is elucidated by invoking a quasi-reversible transformation of the initial SERS-active site into another by an attack, via surface diffusion, of deposited Cd, followed by irreversible unimolecular decomposition of the new site. From the SERS quenching data a value of about 10−17 cm2 s−1 was derived as the surface diffusion coefficient of Cd on the Ag surface. A similar but somewhat different quenching behavior is observed by UPD of Tl.