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, 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, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50190
(Accessed December 1, 2023)