C2H2, ν5ν4
Acetylene, ν5ν4 vibration
Species tag 026505
Date of EntryMay 2007
ContributorsH. S. P. Müller

The data have been published in
(1) Y. Kabbadj, M. Herman, G. DiLonardo, L. Fusina, and J. W. C. Johns, 1991, J. Mol. Spectrosc., 150, 535.
The ν5 lines were also used in the fit. An electronic line list was kindly provided by M. Herman.
Transitions up to J = 40 should be predicted reliably; i.e. they should be found within 3 – 10 times the predicted uncertainties of the line.
With respect to the Mar. 2006 entry, an experimental transition dipole moment for C2H2 was used in the prediction. It was reported by
(2) S. Robert, M. Herman, J. van der Auwera, G. Di Lonardo, L. Fusina, G. Blanquet, M. Lepere, and A. Fayt, 2007, Mol. Phys. 105, 559;
M. Herman, 2007, private communication.
Note: The value has a reported uncertainty of about 20 %; the intensities are thus uncertain to about 40 %. At the lower limit, this value agrees reasonably well with the transition dipole moment 0.0358 D of the corresponding C2D2 vibration determined by Stark measurements and reported by
(3) W. J. Lafferty, R. D. Suenram, and D. R. Johnson, 1977, J. Mol. Spectrosc. 64, 147.
However, the two values can not expected to be the same !
The version number has been retained, the intensity cut-off and the number of lines have changed slightly.
State numbers 1 and 2 refer to v5 = 1 and v4 = 1, respectively. The predictions consider the 3 : 1 intensity ratio of the ortho : para spin modifications. The partition function takes into account v = 0, v4 = 1, and v5 = 1. The individual contributions are available.

Lines Listed273
Frequency / GHz< 7253
Max. J52
log STR0-100.
log STR1-11.3
Isotope Corr.-0.0
Egy / (cm–1)611.69 / 729.15
 µa / D 
 µb / D0.051
 µc / D 
 A / MHz 
 B / MHz35313.60 / 35339.15
 C / MHz 
detected in ISM/CSMno

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