To determine the isotopomer abundance ratio of 13CH4 to 12CH4 by infrared absorption spectroscopy, we selected the v3 P(6) A1 transition of 13CH4 at 2947.6970cm-1 and the V2+ V4 R(6) F 1 transition of 12CH4 at 2947.4246cm -1, which simultaneously satisfy six necessary and desirable conditions, including the higher absorption intensity for the less abundant species, no overlapping with other spectral lines, and small temperature dependence. Then, from the recorded spectra of these transitions using a widely tunable spectrometer based on a difference-frequency-generation light source, we determined the absorption coefficient ratio from the individual absorbance with a precision of 0.3%.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版物ステータス||Published - 2007 4 5|
ASJC Scopus subject areas
- Physics and Astronomy(all)