Widely Tunable External Cavity Quantum Cascade Diode Laser for Multiple Trace Species Measurements

75871-The quantification of the sources and sinks of greenhouse gases, such as carbon dioxide and nitrous oxide, will be essential for the assessment and prediction of the anthropogenic effects of climate change. In addition, measurements of carbon monoxide would help distinguish between the biogenic and anthropogenic sources of these gases. This project will construct an external cavity, quantum cascade diode laser, which will be based on a continuous-wave Fabry-Perot quantum cascade diode laser operating near 4.5 ¿m. The laser will simultaneously measure four gases: carbon dioxide, nitrous oxide, carbon monoxide, and water vapor. Phase I will construct the laser and examine performance characteristics, using wavelength modulation spectroscopy and an astigmatic Herriot cell. The detection sensitivity of CO and N2O will be optimized, without sacrificing the monitoring of CO2 and H2O. Commercial Applications and Other Benefits as described by the awardee: The instrument should find use as part of a network of sensors for measuring the carbon cycle budget on local-to-global scales. The instrument also would have application in measurement of urban air quality and field studies for atmospheric science.