High-Precision Instrument for Carbon-13 and Carbon-12 Isotope Ratios

Large uncertainties in the global carbon budget complicate our understanding of how fossil fuel combustion affects the atmosphere and biosphere. To address these uncertainties, a precise and compact instrument for long-term unattended operation will be developed to measure the isotopic ratios of carbon dioxide. The approach will combine a novel signal and noise cancellation circuit with recently-introduced, continuous wave, distributed feedback lasers operating near a wavelength of 2.7 microns. Phase I will focus on constructing sample and reference cells, and examining the spectral properties of the 13CO2 and 12CO2 lines. The noise canceller circuit will be tested over a range of conditions, and variance measurements over different timescales will be conducted. Commercial Applications And Other Benefits as described by the Applicant: A precise carbon dioxide isotope instrument should find application not only in the atmospheric science and ecosystem research communities but also in geologic monitoring, petrochemical sensing, and biomedical diagnostics. In addition, the successful implementation of the approach would open the door for precise measurements of other trace gas isotopic ratios, including methane and water vapor.