Optical Enhanced Trace Atom Detection for Offgas Monitoring

70052 Current methods for monitoring offgas streams typically combine cumbersome sampling techniques (such as dry filtering and chemical scrubbing) with conventional analytical methods such as gas chromatography (GC), and can require processing times up to hours to achieve necessary sensitivity levels. As such, these approaches are not ideal for either in situ process optimization, hazard assessment, or the remote monitoring of transient emissions. In particular, the monitoring of specific toxic substances such as mercury requires a method that combines high-sensitivity with the ability to accurately measure absolute concentrations in real time. This project will develop technology to fulfill these requirements by using low-cost, readily available hardware, such as standard Atomic Absorption (AA) lamp light sources. This technology is based on the use of optical cavities to significantly enhance the absorption of radiation by the species of interest within the cavity, thereby increasing the sensitivity of the apparatus. In Phase I, a commercial atomic absorption spectrophotometer will be adapted with new cavity enhancement optics, and a series of atomic absorption measurements of a selected atomic species will be made over a range of standard sample concentrations and for a range of cavity conditions. The results will be compared to that obtained using conventional AA techniques and be used to design a Phase II prototype instrument. Commercial Applications and Other Benefits as described by the awardee: The technology should be most valuable in making ultra-sensitive determinations of absolute concentrations of atomic species, particularly metals, in the part-per-billion to the part-per-trillion concentration range. Targeted markets include both academic and corporate institutions presently served by conventional AA instruments.