Best pair of 3.3-μm-band transitions for isotopomer abundance ratio measurements of13CH4 to12CH4

Kenji Anzai, Hiroyuki Sasada, Naohiro Yoshida

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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%.

Original languageEnglish
Pages (from-to)1717-1721
Number of pages5
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number4 A
Publication statusPublished - 2007 Apr 5


  • Absorption spectroscopy
  • Difference frequency generation
  • Isotope analysis
  • Methane
  • Mid-infrared

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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