Removal of Carbonaceous Contamination from SERS-Active Silver by Self-Assembly of Decanethiol.

The presence of carbonaceous contamination on common surface-enhanced Raman scattering (SERS) surfaces has been a primary limitation to the analytical utility of SERS; background contamination significantly affects reproducibility and often determines the limit of detection. Due to the strong interaction between thiols and Ag or Au, self-assembly of alkanethiols onto these metals results in the displacement of "adventitious material" from the metal. The cleaning procedure presented here utilized self-assembly of decanethiol on an electrochemically roughened Ag foil for removal of surface contamination. The self-assembled layer was subsequently removed by rapid oxidation with ozone, followed by rinsing in methanol. The clean Ag surface exhibited a tremendously improved background and a 3-fold increase in the enhancement factor for a probe molecule.