Spectroscopic isotope ratio measurement of doubly-substituted methane

Kiyoshi Tsuji, Hiroaki Teshima, Hiroyuki Sasada, Naohiro Yoshida

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We have determined the isotope ratios of 13CH3D /12CH3D as well as 13CH3D / 12CH4 with an uncertainty of ∼20‰ using a sensitive difference-frequency-generation spectrometer in the 3.4 μm region. Cooling the absorption cell drastically reduces overlap of the 13CH3D lines with the other abundant isotopic lines, and the extensive tunability of the spectrometer enables us to access transition pairs appropriate for isotope ratio measurements. We measure the intensity of the 13CH3D ν4 RP (7, 0) line, the 12CH3D 2ν5 RQ (9, 0) line, and the 12CH4 ν24 R(10) F 2 line at 2953 cm-1 as well as the 13CH 3D ν4 PP (6, 3) line and the 12CH4 ν3 P (6) E line at 2955 cm -1 because they have similar transition frequencies, absorption strengths, and low state energies.

Original languageEnglish
Pages (from-to)43-46
Number of pages4
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Publication statusPublished - 2012 Dec
Externally publishedYes


  • Clumped isotope
  • Difference frequency generation
  • Doubly substituted isotopologue
  • Laser spectroscopy
  • Methane
  • Molecular spectroscopy

ASJC Scopus subject areas

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Spectroscopy


Dive into the research topics of 'Spectroscopic isotope ratio measurement of doubly-substituted methane'. Together they form a unique fingerprint.

Cite this