A High-Vacuum-Cell Approach to SERS Studies of Thin Films on Nonmetallic Surfaces

Abstract

A high-vacuum cell designed for obtaining surface-enhanced Raman scattering (SERS) spectra of thin films on nonmetallic surfaces is described. The cell is shown to improve one's ability to obtain SERS spectra with acceptable S/N ratios and drastically reduced interference from sample alteration and/or bands typically assigned to graphitic carbon. This cell forms the basis of a pragmatic approach to obtaining SERS spectra from interfacial systems that applied surface scientists will likely be faced with in their work. We have applied this new sampling approach to the study of thin films of polystyrene, palmitic acid, and cetyltrimethylammonium bromide deposited on Si surfaces.

Surface‐enhanced Raman scattering from polystyrene on gold clusters

“…However, SERS may contribute to an understanding of its thermal decomposition, [26] especially if the metallic SERS substrate does not alter the usual mechanistic pathway by participating chemically in the degradation process. It has been suggested that reactions involving silver catalyze polystyrene degradation during SERS; [26,27] but our SERS substrates, which are composed of unreactive gold, yield no fewer decomposition peaks than SERS substrates composed of silver. [26,27] Thus we provide evidence that silver substrates do not participate, chemically, in the degradation process.…”

“…It has been suggested that reactions involving silver catalyze polystyrene degradation during SERS; [26,27] but our SERS substrates, which are composed of unreactive gold, yield no fewer decomposition peaks than SERS substrates composed of silver. [26,27] Thus we provide evidence that silver substrates do not participate, chemically, in the degradation process.…”

“…[26,27] In the current work, gold clusters were used as the substrate for SERS and degradationproduct bands similar to those presented in Refs. [26,27] were obtained.…”

“…[26,27] In the current work, gold clusters were used as the substrate for SERS and degradationproduct bands similar to those presented in Refs. [26,27] were obtained. If our gold clusters are chemically inert, appearance of these two bands in our spectra would suggest that catalysis by silver is unnecessary and heating of the SERS substrate is sufficient to cause uncatalyzed degradation.…”

“…We propose that heating of the SERS substrate (in the presence of O 2 [26,27] ) is sufficient to cause uncatalyzed (oxidative [26,27] ) degradation.…”