Stable Isotopic Analysis of Atmospheric Methane by Infrared Spectroscopy by Use of Diode Laser Difference-Frequency Generation
M. E. Trudeau, Pin Chen, G de Andreade Garcia, Leo W. Hollberg, P P. Tans
An infrared absorption spectrometer has been constructed to measure the stable isotopic composition of atmospheric methane samples. The spectrometer employs periodically poled lithium niobate (PPLN) to generate 15 W of tunable difference frequency radiation from two near infrared diode lasers that probes the 3 rotational-vibrational band of methane at 3.4 microns. To enhance the signal, methane is extracted from 25 L of air using a cryogenic chromatographic column and is expanded into the multipass cell for analysis. A measurement precision of 12 is demonstrated for both 13C and D.
, Chen, P.
, de Andreade Garcia, G.
, Hollberg, L.
and Tans, P.
Stable Isotopic Analysis of Atmospheric Methane by Infrared Spectroscopy by Use of Diode Laser Difference-Frequency Generation, Applied Optics
(Accessed March 1, 2024)