Hemispherical Mercuric Iodide Detector

65821 Aircraft measurements of ammonia and nitric acid can provide critical information on the sources and sinks of these atmospheric nitrogen species. This is important in understanding air quality, aerosol formation, visibility, and the impact of energy production and usage on global climate change. This project will develop a compact tunable infrared laser differential absorption spectrometer. Based on recent advances in room temperature pulsed quantum cascade lasers, it will greatly improve the sensitivity of real-time airborne measurements for the detection of ammonia and nitric acid at the 10 parts-per-billion level. In Phase I, the sensitive detection of nitric acid with pulsed quantum cascade lasers will be simulated. A pulse shaping network for decreasing the laser width will be developed to improve sensitivity. Sampling issues, including inlet design and wall loss, will be explored. Commercial Applications And Other Benefits as described by awardee: A sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection should have wide benefits for environmental research, medical diagnostics, and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication.