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Carbon association of surface‐enhanced Raman scattering (SERS) by pyridine on gold electrodes: A Raman and Auger spectroscopic study
Author(s) -
Mernagh Terrence P.,
Cooney Ralph P.,
Spink John A.
Publication year - 1985
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250160110
Subject(s) - raman scattering , auger electron spectroscopy , raman spectroscopy , pyridine , surface enhanced raman spectroscopy , analytical chemistry (journal) , chemistry , electrode , auger , carbon fibers , materials science , photochemistry , organic chemistry , optics , physics , atomic physics , composite number , nuclear physics , composite material
Surface‐enhanced Raman scattering (SERS) by pyridine on gold electrode surfaces to arise from the adsorption of pyridine in or on surface carbon present after the oxidation‐reduction cycle (ORC). Similar Raman ring‐breathing mode spectra for both gold and silver electrodes and sols indicate a common intensely scattering phase which is independent of the metal substrate. The common phase proposed is [carbon‐pyridine]. Auger electron spectroscopy indicates that the SERS spectrum arises from a surface microzone having a C to Au ratio of ca 7. Cathodic elimination of microzone carbon results in the elimination of pyridine SERS. Carbon‐enriched (sputtered) gold surfaces exhibit the same ring‐breathing mode pattern as for the conventional SERS surface. Laser carbonization effects are suggested by differences in the SERS intensities observed for the presence and absence of laser flux during the ORC. Laser decarbonization appears to be the origin of the characteristic decay of SERS from gold electrodes. It is proposed that the decay is instantaneous for 514.5 nm Ar + excitation and slower for 647.1 nm Kr + . Differences in pyridine SERS intensities from silver and gold electrodes are attributed to differences detected by Auger spectroscopy in the extent of laser microzone carbonization. On the basis of these findings Au/pyridine SERS has been classified as Type I.