Ultra-Sensitive Raman Detector: A SERS Spectrometer

Surface-Enhanced Raman Spectroscopy (SERS), a Raman technique that detects enhanced signals from analytes adsorbed to roughened metals, is promising as a trace analyte detector, with reports of single molecule detection. Since SERS directly measureschemical bonding structure, potential for false positives in field analysis is minimal. There are many roughened-metal formats (colloids, films, electrodes, etc.) by which the SERS measurement can be made; every researcher has modified a Raman instrumentto accommodate their particular SERS experiments. There is no existing spectroscopic system fully optimized for SERS analysis and with sampling flexibility to accommodate all metal formats. This program will develop a universal SERS instrument that hasoptimal sensitivity and can accommodate SERS in a laboratory or field environment. The Phase I program evaluated and determined an appropriate spectrograph and determined the optimum angles of analysis for a fiber optic-based SERS system. In addition, weevaluated the effects of substrate angle with respect to an aerosol stream for maximal adsorption. In the Phase II program, we will fabricate a complete prototype that will be a full range, high resolution SERS spectrograph capable of 1) field orlaboratory use and 2) using any desired SERS substrate representation through modular sampling accessories.Small and inexpensive Raman instrumentation will bring new commercial applications of the method, including quality control analysis, processcontrollers, forensic instruments for identifying illegal substances, and air and water monitors.