The analysis and the measurements were presented by
(1) V. V. Ilyushin, O. Zakharenko, F. Lewen, S. Schlemmer, E. A. Alekseev, M. Pogrebnyak, L.-H. Xu, R. M. Lees, A. Belloche, K. M. Menten, R. Garrod, and H. S. P. Müller, 2020, Can. J. Phys. 98, in press.
The data in the 1.1 – 1.5 THz region are based on spectral recordings published by
(2) L.-H. Xu, R. M. Lees, G. T. Crabbe, J. A. Myshrall, H. S. P. Müller, C. P. Endres, O. Baum, F. Lewen, S. Schlemmer, K. M. Menten, and B. E. Billinghurst, 2012, J. Chem. Phys. 137, Art. No. 104313.
Experimental microwave and millimeter-wave transition frequencies have not been merged. The list with reference labels can be accessed in the Cologne Spectroscopy Data section.
The calculated frequencies have been truncated such that they should be reliable throughout.
Please note that the vibrational identifiers correspond in the present calculation to the torsional quantum number m. The values 0 and 1 correspond to A and E symmetry lines, respectively, of v_t = 0. The corresponding values for v_t = 1 are –3 and –2, those for v_t = 2 are 3 and 4. The signs of K_a designate the parity for A symmetry lines; for E symmetry lines, they designate in the picture of a degenerate state of a symmetric rotor.
Lower state energies are given referenced to the J = K = 0, A, v_t = 0 level, which is about 112 cm^–1 above the bottom of the torsional potential well.
Please note that the partition function was scaled from that of the main isotopic spcies.
The experimental ground state dipole moment was derived from that of the main species reported in
(3) S. Tsunekawa, I. Taniguchi, A. Tambo, T. Nagai, T. Kojima, and K. Nakagawa, 1989, J. Mol. Spectrosc. 134, 63.