Dr. Adam J. Fleisher
Research Chemist
National Institute of Standards and Technology
Achieving high accuracy in molecular spectroscopy requires both precise instrumentation and highly controlled sample conditions. Here we report continuous-wave laser cavity ring-down spectroscopy of 14C, 13C and 12C isotopologues of CO2, laboratory measurements which enable the retrieval of absolute isotopic amounts (14CO2) and amount ratios (13C/12C) within a sample. Leveraging highly accurate experimental measurements and ab ini-tio calculations of transitions intensities, we explore the gas-calibration-free optical sensing of trace isotopologues in both pure CO2 and CO2-in-air, as well as propose a path towards artifact-free scales in carbon isotope analysis with traceability to true invariants of nature.
