Instrument and materials development in Raman spectroscopy detection and imaging techniques for planetary explorations

Abstract

Robust, tunable Surface enhanced Raman spectroscopy (SERS) substrates were created using the Langmuir-Blodgett technique. Initial studies of Langmuir-Blodgettry were done with arachidic acid to optimize monolayer deposition parameters. Hydrophilic and hydrophobic glass substrates were prepared and coated with arachidic acid. SERS monolayer substrates were then made from Ag nanostructures. Deposition of Ag nanoparticles using the Langmuir Blodgett technique resulted in clusters of Ag monolayers. The films were capable of SERS for Rhodamine 6G (R6G) and a range of biomolecules. Raman imaging of these films revealed the overall distribution of the SERS effect. In comparison of the enhancement performances, Ag nanowires were also deposited on glass substrates using Langmuir Blodgettry. The resulting substrate consisted of oriented bundles of Ag nanowires. SERS of R6G was observed on these bundles when the polarization of light was longitudinal to the wire axis. Raman imaging showed the distribution of hotspots on the nanowire bundles.