The spectrum of CH3OH between 100 and 200 cm−1: Torsional and “forbidden” transitions

Abstract In the framework of a systematic investigation of the infrared and far infrared spectrum of CH3OH by high-resolution Fourier transform spectroscopy, we present a catalog of 6000 absorption lines between 100 and 200 cm−1 (which means practically all the measured lines in this region which are above a reasonable peakfinder threshold), and a list of 955 recently assigned lines below 100 cm−1, which had not been included in a previous paper. The Taylor expansion coefficients for evaluating the energies of the levels involved in the transitions are also given. Most of the lines occurring in the 100–200 cm−1 region involve torsionally excited states. Another interesting feature of this region is the presence of a forbidden Q branch (Δn = 1 and ΔK = 0 simultaneously). Two further forbidden Q branches, occurring at higher wavenumbers, are also presented.

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