Compact Quantum Cascade Laser-Based Field Sensor for CO2 Isotope Measurements

70127S02-II Measurement of atmospheric concentrations of stable CO2 isotopes can provide new understanding of the dynamics of CO2 exchange between the atmosphere and terrestrial ecosystems on several scales. On the local scale, such measurements enable the study of net ecosystem exchange of CO2. On larger scales, continental to global, isotopically resolved concentration measurements of atmospheric CO2 could be used to monitor the partitioning of CO2 between the major surface sinks (i.e., the oceans) and the terrestrial biosphere. This project will design, develop, and demonstrate a new, high sensitivity, optical absorption spectrometer to monitor trace gas species, such as the major stable isotopes of carbon dioxide. In Phase I, a quantum cascade laser was coupled with a high sensitivity detection system, and the required precision for monitoring the major stable isotopes of CO2 was demonstrated. A complete conceptual design for a compact, lightweight sensor, particularly well-suited for field monitoring, was developed. Phase II will design, fabricate, test, and field-demonstrate a quantum cascade laser-based sensor for the major stable isotopes of CO2. A second sensor for CH4 also will be developed and field-demonstrated. Commercial Applications and Other Benefits as described by 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.