TY - JOUR
T1 - Spectroscopic isotope ratio measurement of doubly-substituted methane
AU - Tsuji, Kiyoshi
AU - Teshima, Hiroaki
AU - Sasada, Hiroyuki
AU - Yoshida, Naohiro
N1 - Funding Information:
We are grateful to Dr. Keita Yamada in Tokyo Institute of Technology for critical reading of the manuscript and valuable comments and to SENTAN, Japan Science and Technology, for financial support. This work is also supported by the Global Environment Research Fund (A-0904) of the Ministry of the Environment, and Grant-in-Aid for Scientific Research (S-23224013), the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
PY - 2012/12
Y1 - 2012/12
N2 - 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 ν2+ν4 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.
AB - 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 ν2+ν4 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.
KW - Clumped isotope
KW - Difference frequency generation
KW - Doubly substituted isotopologue
KW - Laser spectroscopy
KW - Methane
KW - Molecular spectroscopy
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U2 - 10.1016/j.saa.2012.08.028
DO - 10.1016/j.saa.2012.08.028
M3 - Article
C2 - 22982387
AN - SCOPUS:84866000303
SN - 1386-1425
VL - 98
SP - 43
EP - 46
JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
ER -