A Laser-based Instrument Platform for Measuring Methane and Other Trace Gases

78618S Robust and reliable trace-gas analyzers (e.g., for isotopic carbon, methane, nitroxide, ammonia, etc.), suitable for long-term measurements, are not commercially available. Such analyzers are needed to achieve a better understanding of the global budget of these trace gases and to quantify their exchanges between the atmosphere and the terrestrial biosphere. This project will develop a tunable, diode-laser-based instrument platform using newly-developed laser technology. The new instrument platform will be applied first to methane analysis using currently available communication lasers. Phase I will determine the necessary characteristics of the methane sensor, optimize the configuration for the multiple-path optical cell, determine mechanical stability, determine the durability of exposed optics, evaluate a Distributed Feedback laser and a Vertical Cavity Surface Emitting laser, and build a working test platform to verify the design. Commercial Applications and other Benefits as described by the awardee: The lack of robust and reliable methane analyzers has limited the measurement of methane emission from terrestrial ecosystems to short-period campaigns only, ranging from a few weeks to a couple of months. With the new instrument platform, measurements can be made year-round with minor maintenance. The platform should also be adaptable to the analysis of other trace gases and isotopic elements (including ammonia, nitroxide, carbon isotope, and oxygen isotope) when appropriate lasers become available.