Description: A new technique is proposed for improved trace gas detection and measurement that combines the high absorption depths afforded by mid-infrared Integrated Cavity Output Spectroscopy (ICOS) with the added precision and sensitivity of Frequency Modulated Spectroscopy (FMS). To our knowledge, the two-tone FM technique described and prototyped in this proposal is the first demonstration of this combination. This proposal requests funding to advance on the breakthrough preliminary work shown here and to fully realize FM ICOS as a means to achieve one a one order of magnitude increase in detection precision compared to the very sensitive ICOS technique, enabling a new era of trace gas quantification including isotope ratio determinations of carbon, nitrogen and oxygen species.

Benefits: Several high-demand private sector applications are currently limited by spectroscopic sensitivity may be enabled if the breakthrough sensitivity demonstrated here is fully realized. One example would be the realization of reliable, user-friendly analysis of exhaled breath. The application requires the measurement of CO, NO, ketones and other small molecules simultaneously in order for physicians to make determinations about metabolic function in diabetics and other patients with unusual metabolic activity (cancer, asthma, etc...).

This technology has the potential to augment the sensitivity of NASAs existing commercial options with minimal added size, power, or weight, thereby allowing higher sensitivity in a similar package or the miniaturization of instruments that function at today's limits of detection. For example, the spectroscopic technique here, while quite generalizable, could be used to produce very small carbon isotope ratio spectrometers for the monitoring of surface fluxes of gases such as CH4, CO2, N2O, etc... Similarly, the potential exists for higher sensitivity measurements of stratospheric tracers such as CO, N2O, O3, and CH2O. Finally, the enhanced technique proposed here would allow for the measurement of poisonous gases such as CO, NO, NO2, SO2 in environments ranging from volcano plumes to urban pollution and environmental compliance in primary energy generation.