Abstract
A method for determining the relative concentration of 13C/12C isotopes by the vibrational-rotational spectrum of CO2 molecule absorption in the range near 2 µm was proposed. The use of the entire region of the diode laser tuning (∼7 cm−1) and multivariate linear regression for spectrum approximation allow measurements at atmospheric pressure. The laser frequency is additionally stabilized by injection current variation. The ultimate sensitivity of the setup, determined by the plot of the squared Alan variance, is 0.03% for 2-min signal acquisition. The system does not contain elements cooled by liquid nitrogen and can be used in medical diagnostics.
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References
E. S. Mironchuk, I. V. Nikolaev, V. N. Ochkin, et al., Kvant. Elektron. 39, 388 (2009) [Quantum Electron.].
Additional information
Original Russian Text © E.S. Mironchuk, 2010, published in Kratkie Soobshcheniya po Fizike, 2010, Vol. 37, No. 6, pp. 28–30.
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Mironchuk, E.S. Measurement of the 13CO2/12CO2 concentration ratio in exhaled air by diode laser spectroscopy. Bull. Lebedev Phys. Inst. 37, 180–181 (2010). https://doi.org/10.3103/S1068335610060072
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DOI: https://doi.org/10.3103/S1068335610060072