Ethenone, ketene
Species tag 042501
Date of EntryNov. 2003
ContributorH. S. P. Müller

The lines were taken from
(1) H. R. Johnson and M. W. P. Strandberg, 1952, J. Chem. Phys. 20, 687;
(2) B. Fabricant, D. Krieger, and J. S. Muenter, 1977, J. Chem. Phys. 67, 1576;
and (3) R. D. Brown, P. D. Godfrey, D. McNaughton, A. P. Pierlot, and W. H. Taylor, 1990, J. Mol. Spectrosc. 140, 340.
Transition frequencies by T. Y Wang, K. M. T. Yamada, and L. Nemes, which were used in
(4) J. W. C. Johns, L. Nemes, K. M. T. Yamada, T. Y Wang, J. L. Domenech, J. Santos, P. Cancio, D. Bermejo, J. Ortigoso, and R. Escribano, 1992, J. Mol. Spectrosc. 156, 501,
were kindly communicated by L. Nemes.
The 101 – 000 line was taken from
(5) D. H. Sutter and H. Dreizler, 2000, Z. Naturforsch. 55a, 695.
Additional lines used in
(6) A. Guarnieri and A. Huckauf, 2003, Z. Naturforsch. 58a, 275,
were kindly communicated by A. Huckauf.
Some higher order centrifugal distortion constants were kept fixed to values from 4. Predictions fot higher values of Ka should be viewed with caution.
At low temperatures, it may be necessary to discern between ortho-H2C2O and para-H2C2O. The ortho states are described by Ka odd, the para states by Ka even. The nuclear spin-weights are 3 and 1 for ortho-H2C2O and para-H2C2O, respectively. The JKaKc = 111 level is the lowest ortho level. It is 9.7395 cm–1 above ground.
Dec. 2011: Separate para and ortho predictions are available along with separate para and ortho partition function values. Note: the spin-weight of 3 for the separate ortho predictions has been eliminated.
The 1H hyperfine splitting may be resolved at low temperatures, low frequencies, and for low values of J. Therefore, a separate hyperfine calculation is provided up to J = 9 for transitions with ΔJ = 0 and Ka = 1 plus the two J = 2 – 1 transitions along with separate ortho partition function values.
The dipole moment was reported in 2.

Lines Listed2027
Frequency / GHz< 1771
Max. J88
log STR0-10.0
log STR1-7.0
Isotope Corr.0.0
Egy / (cm-1)0.0
 µa / D1.42215
 µb / D 
 µc / D 
 A / MHz282089.
 B / MHz10293.321
 C / MHz9915.904
detected in ISM/CSMyes

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