Development of a High Precision, Quantum Cascade Laser-Based Detector for Carbon Dioxide and Carbon Monoxide

70814B02-II Measurements of atmospheric concentrations of CO2 and CO from aircraft and from remote sites play a central role in observational strategies intended to quantify the sources and sinks of carbon and to control global warming from greenhouse gas emissions. Improved measurement techniques that are highly sensitive, automated, and robust are needed to quantify changes in the carbon content of the atmosphere and to assess mechanisms of exchange with the Earth¿s surface. This project will develop an instrument to measure CO2 and CO, using newly available ¿quantum cascade¿ lasers that operate in the mid-infrared spectral region without cryogenic cooling. Phase I demonstrated the feasibility of using near-room-temperature pulsed-quantum-cascade lasers and detectors for high precision absorbance measurements. A novel, dual-sampling cell ratio technique for CO2 was developed that could determine the difference between the two cells with a precision of 70 ppb. The capability to determine CO with a precision better than 1 ppb also was demonstrated. Phase II will design, construct, and demonstrate a prototype instrument for CO2 that can be deployed at ground-based, remote locations for continuous autonomous measurements. With optional supplemental Phase II funding, the instrument could be flight-hardened and deployed from an aircraft platform. Commercial Applications and Other Benefits as described by awardee: An improved instrument for CO2 measurements would be widely applicable to environmental and ecological research in addition to the measurement of atmospheric trace gases. A sensitive, cryogen-free, mid-infrared absorption spectrometer also would have commercial applications in medical diagnostics and industrial process monitoring for detecting a wide variety of gas phase molecules.