Spectroelectrochemical investigations of the interaction of ethyl xanthate with copper, silver and gold: II. SERS of xanthate adsorbed on silver and copper surfaces

Raman spectroscopy has been applied to the investigation of the interaction of ethyl xanthate with silver and copper surfaces. SERS spectra recorded in situ and on emersed electrodes have confirmed the conclusion of previous studies that ethyl xanthate is chemisorbed on these metals at potentials below the reversible value for the corresponding metal-metal ethyl xanthate couple without change in its molecular integrity. The stretching vibrations of the hydrocarbon groups in the xanthate molecule were found to be suppressed when SERS spectra were recorded in situ, but the corresponding rocking and deformation vibrations were unaffected. The hydrocarbon stretching vibrations were strong in the spectra from emersed electrodes. The difference between the spectra from surfaces in the two environments is discussed in terms of absorption of the signal by the overlaying water layer and the hydrophobic nature of chemisorbed xanthate. (C) 1998 Elsevier Science B.V.