The observed lines are from
(1) A. Moïses, D. Boucher, J. Burie, J. Demaison, and A. Dubrulle, 1982, J. Mol. Spectrosc. 92, 497;
from
(2) M. Bester, M. Tanimoto, B. Vowinkel, G. Winnewisser, and K. M. T. Yamada, 1983, Z. Naturforsch. 38a, 64;
and from
(3) M. Bester, PhD thesis, 1984, Universität zu Köln.
At low J, the K-splitting was not resolved. Because of the large residuals, these lines were not used in the fit. Furthermore, quadrupole splitting due to the ¹⁴N nucleus may be resolvable for low J. With respect to the June 2000 entry, a separate hyperfine calculation is provided with J' up to 15 and K_a up to 6 along with partition function values. The version number has been retained.
The purely K-dependent parameters (A and D_K), needed to obtain reasonable intensities, were taken from CH₃CN;
(4) R. Antilla, V.-M. Hornemann, M. Koivusaari, and R. Paso, 1993, J. Mol. Spectrosc., 157, 198.
The dipole moment is from
(5) M. Bester, K. M. T. Yamada, G. Winnewisser, W. Joentgen, H.-J. Altenbach, and E. Vogel, 1984, Astron. Astrophys. 137, L20.
At low temperatures, it may be necessary to discern between A-CH₃C₃N and E-CH₃C₃N. 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-CH₃C₃N with K>0 and all other states, respectively. The J_K = 1₁ state is the lowest E state. It is 5.3424 cm^–1 above ground.