SURFACE-ENHANCED RAMAN-SPECTROSCOPY USING COMMERCIALLY AVAILABLE AU COLLOIDS

Surface-enhanced Raman spectroscopy (SERS) has received considerable attention in recent years as an analytical technique and was the subject of a recent review article. Many different types of SER substrates have been described for analytical purposes including metal electrodes, metal colloids, and metal-coated substrates, such as Ag-coated microspheres and microspheres deposited on filter paper, as well as Ag-coated paper and fumed silica. To eliminate the preparation and sorting steps required for the use of Au colloids, we are investigating the use of some commercially available Au colloids for SERS. Although many companies supply these colloids, we did not attempt to compare colloids made by different manufacturers, but limited our search to a single supplier (PolySciences, Inc). Tests were limited to a few concentrations and colloid sizes, and one was found that gave large SER enhancements using 632-nm and 785-nm excitation.