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Nuclear-spin conversion analysis of ν2 + ν4 combination band of crystalline methane in phase II
Takeru Sugimoto1, Koichiro Yamakawa2
1Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
Abstract:
We conducted reflection-absorption infrared spectroscopy in an ultrahigh vacuum and observed the ν2 + ν4 combination band of crystalline methane in phase II, where the rotating and librating species coexist. We analyzed the time- and temperature-dependence of the spectrum due to the nuclear-spin conversion of methane to update the assignment of the rotational and librational structure of this band. The conversion analysis performed in the present work will also be applicable to the detailed assignments of overtones and other combination bands.
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