Optical Carbon Dioxide Field Isotope Ratiometer

78093S Anthropogenic greenhouse gas emissions are best quantified by determining the carbon dioxide isotope ratios. The precision required represents a challenge to optical measurement techniques under field deployment conditions. This project will develop a compact, rugged, mid-infrared spectrometer capable of determining isotopic carbon dioxide ratios at atmospherically relevant levels. In Phase I, a mid-infrared spectrometer for detection of carbon dioxide at 4.3 microns will be constructed, based on a pulsed quantum cascade (QC) laser. The sensitivity, selectivity, and precision of the instrument for isotopic carbon dioxide analysis will be determined using a novel cavity enhancement cell, specifically suited for QC lasers. An isotopic abundance precision of about 1 'per mil' is expected in less than one minute. The Phase II development will result in field-ready prototypes for making measurements over hours to days. Commercial Applications and Other Benefits as described by the awardee: The targeted application for measuring greenhouse gas emissions is of high intrinsic value for assessment of global warming. In addition, the technology should be useful in general trace gas detection applications in multiple industries. Examples include process gas analysis, breath-based medical diagnostics, and environmental regulatory compliance.