Use of polarization-dependent SERS from scratched gold films to monitor the electrochemically-driven desorption and readsorption of cysteine

The electrochemically-driven desorption and readsorption of cysteine, on scratched gold surfaces placed in a highly concentrated cysteine solution, was investigated. The ordinary Raman signal from cysteine in solution was significant relative to the SERS signal from adsorbed cysteine. However, the SERS signal was isolated from the ordinary Raman background by subtracting the signal obtained with the incident laser light polarized along the scratch (ordinary Raman) from the signal obtained with it polarized across the scratch (ordinary Raman + SERS). The method described here is applicable to other electrochemical systems where signal from solution-phase species can interfere with, or even overwhelm, signal from the adsorbate. For example, it may be used in SERS studies of water or ionic liquid structure in the double-layer region.