Carbon Contamination at Silver Surfaces:  Surface Preparation Procedures Evaluated by Raman Spectroscopy and X-ray Photoelectron Spectroscopy

Abstract

The quantity and chemical nature of carbonaceous impurities remaining on polycrystalline Ag surfaces after preparation depend on the protocol used for cleaning. The effectiveness of several preparation protocols was investigated in this study: mechanical polishing with successively finer grades of alumina, Ar + sputtering, chemical polishing, and chemical polishing followed by Tl underpotential deposition. The impurities detected on polycrystalline Ag surfaces subjected to these preparation procedures are carbon, oxygen, and aluminum, and these are qualitatively and quantitatively identified with X-ray photoelectron spectroscopy. With Raman spectroscopy, these carbonaceous impurities are qualitatively identified as graphite, hydrocarbon, and cyanide species, the last of these being present only on the chemically polished surfaces.

Inherent Complexities of Trace Detection by Surface‐Enhanced Raman Scattering

“…[119] To confound matters further, it has been shown that for silver surfaces prepared by a variety of methods, carbon is always present. [120] There have been attempts to remove contaminants. Norrod and Rowlen have demonstrated that the use of alkanethiols can displace the surface contaminants on SERS-active silver foil, and improve enhancement by a factor of three.…”

Electrochemical preparation of silver and gold nanoparticles: Characterization by confocal and surface enhanced Raman microscopy

“…As revealed by the measurements, the Raman active species were graphite and nanocrystalline carbon, a typical experience in surface analysis. In the literature, the origin of carbon contamination is discussed in detail [11,12]. One general source of contamination is the metal preparation procedure.…”

What is observed in single molecule SERS, and why?

“…Higher quality rinsing resulted in the disappearance of the carbon Raman bands. The influence of silver surface preparations on carbon contamination have been evaluated by Raman and x-ray photoelectron spectroscopy by Taylor et al 53 The characteristic Raman bands of sp 2 -carbon are also observed in amorphous carbon-hydrogen (a : C-H) films, for instance grown by electric discharge in C 2 H 2 gas. 54 Figure 3(d) gives the time-invariant SERS spectrum assigned by Bjerneld et al 21 to tyrosine (Tyr) adsorbed on 30 nm Ag particles.…”