HC4NC
isocyanobutadiyne
Species tag 075501
Version3*
Date of EntryDec. 2024
ContributorH. S. P. Müller

The observed frequencies and the theoretical value for the dipole moment were taken from
(1) P. Botschwina, Ä. Heyl, W. Chen, M. C. McCarthy, J.-U. Grabow, M. J. Travers, and P. Thaddeus, 1998, J. Chem. Phys. 109, 3108.
With respect to the first entry of May 2001, rest frequencies from astronomical observations were added. With respect to the second entry of Oct. 2020, slightly improved and extended rest frequencies from astronomical observations were taken from
(2) R. Fuentetaja, C. Cabezas, Y. Endo, M. Agúndez, B. Tercero, N. Marcelino, P. de Vicente, and J. Cernicharo, 2024, Astron. Astrophys. 688, Art. No. L29.
The small 14N hyperfine splitting has been resolved in the laboratory experiments.
The calculations should be accurate enough for all observations. They should be viewed with caution if the calculated uncertainties are larger than 0.1 MHz.
14N hyperfine splitting may matter in astronomical observations. Therefore, a separate hyperfine calculation is provided for J' ≤ 14 below 40 GHz. NOTE: The partition function does take into account the spin multiplicity of the 14N nucleus !
The dipole moment is from a quantum chemical calculatioj in (1).

Lines Listed71
Frequency / GHz< 200.0
Max. J71
log STR0-7.5
log STR1-3.0
Isotope Corr. 
Egy / (cm–1)0.0
 µa / D3.25
 µb / D 
 µc / D 
 A / MHz 
 B / MHz1401.182
 C / MHz 
 Q(300.0)13387.4304
 Q(225.0)10040.3048
 Q(150.0)6693.5198
 Q(75.00)3347.0850
 Q(37.50)1673.9990
 Q(18.75)837.4891
 Q(9.375)419.2429
 Q(5.000)224.0641
 Q(2.725)122.5732
detected in ISM/CSMyes


Database maintained by Holger S. P. Müller and Sven Thorwirth, programming by D. Roth and F. Schlöder