A Rugged, Quantum Cascade Laser-Based Cavity Enhanced Spectrometer for Highly Sensitive Trace Gas Measurements in Troposphere

75549-Trace species in the atmosphere, such as carbon monoxide, nitric oxide, formaldehyde, and ethylene, can affect the production of ozone in the troposphere and also impact regional air quality. In particular, the quantification of carbon monoxide, a tracer of human activity, can aid high precision measurements of carbon dioxide, measurements that are important to carbon cycle studies and to global warming research. All of these species can be present in the troposphere at concentrations as low as 100 parts per trillion. New and compact instrumentation is required to make measurements of these trace gases with high specificity and sensitivity from small aircraft. This project will develop a high sensitivity, optical absorption spectrometer to monitor trace species such as carbon monoxide, nitric oxide, formaldehyde, and ethylene. The spectrometer will combine advances in Quantum Cascade laser technology with cavity enhanced absorption methods, resulting in detection sensitivities on the order of 100 pptv. It will be deployable on small research aircraft. During Phase I, a quantum cascade laser will be coupled to a high finesse optical cavity, and the required measurement precision for the ambient monitoring of each target species will be demonstrated. A complete conceptual design for a compact, lightweight sensor that is particularly well suited for airborne monitoring will be developed. Commercial Applications and Other Benefits as described by the awardee: A highly sensitive monitor for trace gases would fulfill a long-standing need in environmental and air quality monitoring. Other applications include combustion emissions analysis, fugitive emissions control, industrial process control, and contraband detection.