Systematic analysis of the Fourier transform spectrum of 13CH3OH between 400 and 950 cm−1

We have investigated a high-resolution Fourier transform (FT) absorption spectrum of the 13CH3OH isotopomer of methanol from 400 to 950 cm−1 with the “Ritz” program. We present the assignments of 7160 transitions, 3021 of which belong to A-symmetry, and 4139 to E-symmetry. These transitions occur between states labeled by K quantum numbers up to 14, and by torsional quantum numbers n up to 4. The “Ritz” program evaluated the energies of the 4684 involved levels with an accuracy of the order of 10−4 cm−1. All of the assigned lines correspond to transitions involving torsionally excited levels within the ground small-amplitude vibrational state.