Isopropanol is the branched isomer of normal propanol. There are two conformers, the doubly degenerate gauche and the singly degenerate anti, also known as trans, which is about 120 K (or 83.4 cm^–1) higher in energy.
A very extensive list of transition frequencies was taken from
(1) A. Maeda, I. R. Medvedev, F. C. De Lucia, E. Herbst, 2006 Astrophys. J. Suppl. Ser. 166, 650.
A modest number of transition frequencies were taken from
(2) E. Hirota, 1979 J. Phys. Chem. 83, 1457.
The present parameter set differs slightly from that in (1). These as well as transitions omitted in (1) could be fit within 50 kHz. The additional lines were kindly provided by A. Maeda. Only a very small number of transition frequencies with large residuals were omitted from the fit. Predicted transition frequencies with uncertainties greater than 0.3 MHz should be viewed with caution. Nevertheless, predictions should be sufficient for all observational purposes.
The partition functions takes into consideration only the ground vibrational states of both conformers. Individual contributions are available. Vibrational correction factors should be available in the near future.
The dipole moment components were reported by
(3) S. Kondo and E. Hirota, 1970 J. Mol. Spectrosc. 34, 97.