In-situ Quantification and Speciation Analysis of Radionuclides via Fiberoptic Surface Enhanced Raman Spectroscopy (SERS)

Real-time, in situ measurement and monitoring tools for interrogating biogeochemical processes in the subsurface environment are critical to assessing remediation performance and site stewardship at many contaminated DOE sites. In particular, in situ quantification and speciation analysis of important radionuclides are essential to facilitate the rapid identification of potential hazards, shorter turn-around times for analytical results, and improved stewardship. Current techniques for monitoring and characterizing radionuclides rely primarily on liquid scintillation counting, ICP-MS, and the limited use of spectrofluorimetry. These techniques often require chemical handling (for example, the use of scintillation cocktails in liquid scintillation counting) or complexing media (such as phosphoric acids) in order to enhance signals and selectivity in fluorimetry. Additionally, these analyses usually require high-cost capital equipment and a lengthy analytical time. This project will develop a new tool for in situ quantification and speciation analysis of radionuclides and other groundwater constituents via fiberoptic surface enhanced Raman spectroscopy (SERS). The specific objectives are to: (1) develop new methods to detect and characterize important radionuclides (such as uranium and technetium) and other groundwater constituents (such as nitrate and sulfate) by exploiting recent breakthroughs in SERS; (b) optimize methodologies to synthesize SERS substrates with improved selectivity and sensitivity; and (3) fabricate a prototype fiberoptic SERS probe that can be interfaced with a portable Raman spectrometer for in situ measurements. Commercial Applications and other Benefits as described by the awardee: A novel SERS technique for monitoring and characterizing radionuclides and other groundwater constituents in the subsurface environment would benefit DOE remediation efforts. The technique also could be used to detect other priority environmental pollutants, such as perchlorate and chlorinated organic compounds, found at many of the industrial and DOD sites. The estimated market is on the order of multi-million dollars per year.