REMOTE FIBER OPTIC SURFACE ENHANCED RAMAN SPECTROSCOPY OF ORGANIC POLLUTANTS IN GROUND AND SURFACE WATERS

ENERGY-RELATED INDUSTRIES CAN BE SOURCES OF ORGANIC POLLUTANTS IN GROUNDWATER, LAKES AND OCEANS WHICH CAN HAVE DEVASTING CONSEQUENCES FOR THE ECOSYSTEM. THE GOAL OF THE PROPOSED WORK IS TO DEVELOP A METHOD FOR REMOTE, IN SITU DETECTION AND SPECIATION OF THESE CONTAMINANTS AT THE PARTS PER BILLION LEVEL AND BELOW. THE PROPOSED DEVICE WOULD BE BASED ON SURFACE ENHANCED RAMAN SPECTROSCOPY (SERS). WITH THIS TECHNIQUES, THE VIBRATIONAL SPECTRA OF MOLECULES ADSORBED ONTO A ROUGHENED METAL SUBSTRATE CAN BE DETECTED WITH HIGH SENSITIVITY, DOWN TO ABOUT 0.1% MONOLAYER SURFACE COVERAGE. ORGANIC MOLECULES IN AQUEOUS SOLUTION ARE PREFERENTIALLY ADSORBED ONTO METAL SURFACES. THE SERS SIGNAL IS OBTAINED FROM RAMAN SCATTERING OFF THE SUBSTRATE USING A VISIBLE LASER SOURCE. REMOTE SENSING WILL BE ACHIEVED USING OPTICAL FIBERS FOR EXCITING THE METAL SUBSTRATE, CONTAINED IN A PROBE HEAD, AND FOR RETURNING THE SCATTERED LIGHT TO A SPECTROGRAPH. THE GOAL OF PHASE I IS TO DETERMINE THE SENSITIVITY OF SERS IN ANALYZING MIXTURES OF ORGANIC POLLUTANTS WHICH ARE BY-PRODUCTS OF COAL GASIFICATION IN AQUEOUS SOLUTION. IF FEASIBILITY IS DEMONSTRATED, PHASE II WOULD BE DEVOTED TO DEVELOPING THE REMOTE SENSING ASPECTS OF THE METHOD.