CCH, v = 0
Ethynyl, X 2Σ+, v = 0
Species tag 025501
Date of EntryJuly 2010
ContributorH. S. P. Müller

The first version of this entry was created in April 2000. It was based on data summarized in
(1) H. S. P. Müller, T. Klaus, and G. Winnewisser, 2000, Astron. Astrophys. 357, L65.
The second entry from Aug. 2009 was based on new rest frequencies for the N = 1 – 0 and 2 – 1 transitions obtained from astronomical observations described in
(2) M. Padovani, C. M. Walmsley, M. Tafalla, D. Galli, and H. S. P. Müller, 2009, Astron. Astrophys. 505, 1199.
Note: Previously used, seemingly more accurate data show considerable off-sets; see (2) for further details.
Besides these data and the submillimeter data from (1), frequencies for the N = 3 – 2 transition were taken from
(3) K. V. L. N. Sastry, P. Helminger, A. Charo, E. Herbst, and F. C. DeLucia, 1981, Astrophys. J. 251, L119.
The third, present entry combines rotational and rovibrational data of several low-lying states. Ground state transitions were taken from the original data in (1–3). The effect of the additional data on the ground state data is negligible.
The v2 = 1 rotational lines were taken from
(4) D. R. Woodward, J. C. Pearson, C. A. Gottlieb, M. Guélin, and P. Thaddeus, 1987, Astron. Astrophys. 186, L14.
Data for v2 = 2, v3 = 1, and for v2 = v3 = 1 were published in
(5) T. C. Killian, C. A. Gottlieb, and P. Thaddeus, 2007, J. Chem. Phys. 127, Art. No. 114320.
ν3 infrared transitions were measured by
(6) H. Kanamori, K. Seki, and E. Hirota, 1987, J. Chem. Phys. 87, 73.
Data for the ν2 + ν3 band were given in
(7) K. Kawaguchi, T. Amano, and E. Hirota, 1988, J. Mol. Spectrosc. 131, 58.
Transitions for 5ν2 and the hot bands 5ν2 – ν2 and ν2 + ν3 – ν2 were published by
(8) H. Kanamori and E. Hirota, 1988, J. Chem. Phys. 89, 3962.
Additional spectroscopic parameters of states up to 2200 cm–1 were taken from
(9) Y.-C. Hsu, J.-M. Lin, D. Papoušek, and J.-J. Tsai, 1993, J. Chem. Phys. 98, 6690;
(10) Y.-C. Hsu, Y.-J. Shiu, and C.-M. Lin, 1995, J. Chem. Phys. 103, 5919;
(11) W.-Y. Chiang, Y.-C. Hsu, 1999, J. Chem. Phys. 111, 1454
or have been estimated from these data. NOTE: The anharmonic interaction between v2 = v3 = 1 and v2 = 5 can only be accounted for approximately using simple assumptions and has thus been ignored as in (8). As hyperfine structure data are available for some states it has been ignored in the energy file. This leads to small differences for the partition function values which can be neglected. Different l-components of a given vibrational state have been treated separately but will appear in the same entry as far as appropriate. Partition function values for only the ground vibrational state are given in parentheses. The partition function values are reliable up to 300 K, quite reasonable up to 500 K, and should be viewed with great caution at higher temperatures.
Predictions should be viewed with increasing caution above 1.5 THz or N > 17.
The dipole moment is from an ab initio calculation by
(12) D. E. Woon, 1995, Chem. Phys. Lett. 244, 45.
It is assumed that vibrational changes are negligible; this may be incorrect. Transition dipole moments were estimated from calculated infrared intensities published by
(13) R. Tarroni and S. Carter, 2004, Mol. Phys. 102, 2167.

Lines Listed363
Frequency / GHz< 4062
Max. J47
log STR0-8.0
log STR1-8.5
Isotope Corr.-0.0
Egy / (cm–1)0.0
 µa / D0.770
 µb / D 
 µc / D 
 Q(1000.)9027.3122 (1914.1407)
 Q(500.0)2085.3195 (956.6166)
 Q(300.0)815.4124 (574.2378)
 Q(225.0)520.4986 (430.9381)
 Q(150.0)304.5078 (287.6888)
 Q(75.00)144.7246 (144.4919)
 Q(37.50)72.9146 (72.9146)
 Q(18.75)37.1437 (37.1437)
 Q(9.375)19.2835 (19.2835)
 Q(5.000)10.9935 (10.9935)
 Q(2.725)6.7735 (6.7735)
detected in ISM/CSMyes

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