C3H, v = 0, v4 = 1, 2Σμ
Propynylidyne, X 2Πr; v = 0 and v4 = 1, 2Σμ
Species tag 037501
Date of EntryMar. 2009
ContributorH. S. P. Müller

The Renner-Teller effect splits the two Σ components of the CCH bending mode ν4 (≈ 600 cm–1) of C3H such that the lower component 2Σμ is only 27.20 cm–1 above the lowest rotational state (N = 1, J = 0.5, F = 0 of the 2Π1/2 ladder). This leads to considerable Coriolis interaction, as shown by
(1) S. Yamamoto, S. Saito, H. Suzuki, S. Deguchi, N. Kaifu, S.-I. Ishikawa, and M. Ohishi, 1990, Astrophys. J. 348, 363.
Additional millimeter wave transitions have ben reported by
(2) C. A. Gottlieb, J. M. Vrtilek, E. W. Gottlieb, P. Thaddeus, and Å. Hjalmarson, 1985, Astrophys. J. 294, L55.
Further low frequency transitions were taken from astronomical observations by
(3) N. Kaifu, M. Ohishi, K. Kawaguchi, S. Saito, S. Yamamoto, T. Miyaji, K. Miyazawa, S.-I. Ishikawa, C. Noumara, S. Harasawa, M. Okuda, and H. Suzuki, 2004, Publ. Astron. Soc. Japan 56, 69.
With respect to the Aug. 2004 entry, additional submillimeter lines have been reported by
(4) M. Caris, T. F. Giesen, C. Duan, H. S. P. Müller, S. Schlemmer, and K. M. T. Yamada, 2009, J. Mol. Spectrosc. 253, 99.
These data do not only include pure rotational transitions, but also transitions between the higher lying 2Π3/2 state and the 2Σμ state. Predictions for the rovibrational transitions between the lower lying 2Π1/2 state and the 2Σμ state, which occur around 1 THz, should be viewed with some caution; the same applies to all transitions having predicted uncertainties much larger than 1 MHz.
The state numbers 0 and 1 refer to the ground vibrational state and the excited v4 = 1, 2Σμ state, respectively.
The dipole moment is from an ab initio calculation by
(5) D. E. Woon, 1995, Chem. Phys. Lett. 244, 45.
A substantial transition dipole moment between v = 0 and v4 = 1 can be expected – a value of 0.5 D was assumed in (1).

Lines Listed5344
Frequency / GHz< 3400
Max. J91
log STR0-8.0
log STR1-7.5
Isotope Corr.-0.0
Egy / (cm–1)0.0, 27.20
 µa / D3.55, 3.55
 µb / D0.5
 µc / D 
 A / MHz 
 B / MHz11189.1, 11212.7
 C / MHz 
detected in ISM/CSMyes

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