The observed lines are from
(1) A. J. Alexander, H. W. Kroto, M. Maier, and D. R. M. Walton, 1978, J. Mol. Spectrosc. 70, 84; and from
(2) W. Chen, J.-U. Grabow, M. J. Travers, M. R. Munrow, S. E. Novick, M. C. McCarthy, and P. Thaddeus, 1998, J. Mol. Spectrosc. 192, 1.
Quadrupole splitting due to the ¹⁴N nucleus has been resolved in the lab for low J.
The purely K-dependent parameters (A and D_K), needed to obtain reasonable intensities, were taken from CH₃CN;
(3) R. Antilla, V.-M. Hornemann, M. Koivusaari, and R. Paso, 1993, J. Mol. Spectrosc., 157, 198.
The dipole moment is an estimate from
(4) M. Bester, K. M. T. Yamada, G. Winnewisser, W. Joentgen, H.-J. Altenbach, and E. Vogel, 1984, Astron. Astrophys. 137, L20.
Predictions above 150 GHz or with K_a > 10 should be viewed with caution. At low temperatures, it may be necessary to discern between A-CH₃C₅N and E-CH₃C₅N. The A states are described by K = 3n, the E states by K = 3n ± 1. The nuclear spin-weight ratio is 2 : 1 for A-CH₃C₅N with K > 0 and all other states, respectively. The J_K = 1₁ state is the lowest E state. It is 5.2995 cm^–1 above ground.