Ultra-Sensitive, Compact Mid-Infrared Spectrometer for Airborne and Ground-Based Atmospheric Monitoring

75785S Recent advances in both mid-infrared laser sources and ultra-sensitive optical detection technologies offer the promise of studying trace atmospheric species such as formaldehyde with unprecedented detail and accuracy. The development of corresponding instrumentation, suitable for both airborne and ground-based monitoring applications, would have a wide ranging impact on our understanding of atmospheric chemistry and dynamics. This project addresses this need by combining a novel tunable single-frequency, mid-infrared laser source with cavity ringdown spectroscopy. The combination will allow many important atmospheric constituents (including formaldehyde, CO, ethylene, acetylene, and N2O) to be monitored with unprecedented sensitivity (less than 25 pptv mixing ratio) in real time (less than 30 seconds). In Phase I, a single-frequency infrared laser source, operating in the 2.65 micron spectral region, was constructed and fully characterized. The source produced up to 3 mW and 30 microwatts with and without a fiber amplifier, respectively. The source was combined with cavity enhanced spectroscopy to demonstrate the sensitive detection of water vapor isotopes. Phase II will significantly refine the infrared laser source as well as the overall apparatus. The apparatus will be integrated into an instrument capable of performing long-term, unattended field measurements of a variety of atmospheric trace species. Commercial Applications and Other Benefits as described by the awardee: The instrument should have a wide ranging impact on our understanding of atmospheric chemistry and dynamics. Commercial applications for the technology include trace gas monitoring, pollution monitoring, and industrial process monitoring.