Ultrasensitive, Portable Isotope Ratio Analyzer

65414 Accurate measurements of stable carbon isotopes in ambient air or soil currently require that samples be brought to a laboratory for analysis. This procedure is labor intensive, very expensive, and time consuming. This project will develop an analytical instrument to provide sensitive, accurate, and precise measurements of stable carbon isotopes and total carbon dioxide in ambient air in real time in the field. The instrument will be based on an emerging technology called cavity ringdown spectroscopy (CRDS) and employ telecommunications-type tunable diode lasers, fiber optics, and the latest developments in microelectronics. Phase I demonstrated the ability to accurately measure the ratio of stable carbon isotopes, carbon 13 to carbon 12, and total CO2 concentration with very high accuracy and sensitivity, using a platform that can be developed into a low-cost and manufacturable instrument. In Phase II, a set of advanced prototype instruments, optimized for this application and suitable for field deployment, will be designed and built. The instruments will be tested against current analytical techniques in both laboratory and field operation settings, and will establish the usefulness of CRDS in atmospheric sampling applications related to biosphere-atmosphere CO2 exchange. Commercial Applications and Other Benefits as described by the awardee: Commercial applications include analytical instrumentation for measurements of carbon sources and sinks (global compliance); metabolic rates in animals, humans, microbes (physiology); water-use efficiency (biology); diet reconstruction (anthropology); climates (geology), and medical diagnostics.