The demonstration of an ultra-sensitive infrared spectroscopic technique for analysis of carbon isotopologues of methane is presented. Using off-axis integrated cavity output spectroscopy (ICOS) near 1294 cm-1, we have achieved a δ13C measurement precision of 1.5 in 1 s and 0.21 in 200 s while sampling dry air with a 12CH4 mixing ratio of 1.846 ppmv. This method will allow for high time response, high-sensitivity stable isotope analysis in the troposphere without the need for sample preconcentration, and could have major implications for better understanding of carbon-cycle dynamics. This work also addresses the relationship between the scanning frequency of the laser, the characteristic cavity frequency, and the line shapes of spectral features in ICOS. © 2010 Springer-Verlag.
CITATION STYLE
Witinski, M. F., Sayres, D. S., & Anderson, J. G. (2011). High precision methane isotopologue ratio measurements at ambient mixing ratios using integrated cavity output spectroscopy. In Applied Physics B: Lasers and Optics (Vol. 102, pp. 375–380). https://doi.org/10.1007/s00340-010-3957-2
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