HCO+, ν2 IR band
Oxomethylium, ν2 IR band
Species tag 029515
Version1*
Date of EntrySep. 2010
ContributorH. S. P. Müller

A combined fit of HCO+, v2 = 0 and 1, has been performed. It has been altered considerably with respect to the Oct. 2005 entry. The v = 0 transitions frequencies have been summarized largely in
(1) F. Tinti, L. Bizzocchi, C. Degli Esposti, and L. Dore, 2007, Astrophys. J., accepted.
Additional high frequency transitions were taken from
(2) V. Lattanzi, A. Walters, B. J. Drouin, and J. C. Pearson, 2007, Astrophys. J., 662, 771.
The uncertainties of these transitions have been increased to 100 kHz because of large residuals compared to predictions from (1); the remainder of the data from that work seems to be judged appropriately or maybe even conservatively. With respect to prediction based on data from (1) only, those from (2) reduce the uncertainties slightly.
The v2 = 1, J = 4 – 3 transitions were taken from
(3) E. Hirota and Y. Endo, 1988, J. Mol. Spectrosc., 127, 527.
Higher-J transitions were provided by (2).
ν2 infrared data from
(4) K. Kawaguchi, C. Yamada, S. Saito, and E. Hirota, 1985, J. Chem. Phys. 82, 1750;
as well as from
(5) P. B. Davies and W. J. Rothwell, 1984, J. Chem. Phys. 81, 5239
were also used in the fit.
Predictions beyond J = 40 should be viewed with caution.
The transition dipole moment has been estimated from an ab initio calculation by
(6) J. M. L. Martin, P. R. Taylor, and T. J. Lee, 1993, J. Chem. Phys. 99, 286.
The partition function takes into account both vibrational states; individual contributions are given in parentheses.

Lines Listed136
Frequency / GHz< 28847
Max. J46
log STR0-100.0
log STR1-10.0
Isotope Corr.-0.0
Egy / (cm–1)0, 829.72
 µa / D 
 µb / D0.12
 µc / D 
 A 
 B44594.43, 44677.15
 C 
 Q(500.0)277.0975 (234.1599, 42.9376)
 Q(300.0)145.8285 (140.5807, 5.2478)
 Q(225.0)106.5508 (105.5055, 1.0453)
 Q(150.0)70.4887 (70.4395, 0.0492)
 Q(75.00)35.3833 (35.3833)
 Q(37.50)17.8601 (17.8601)
 Q(18.75)9.1023 (9.1023)
 Q(9.375)4.7298 (4.7298)
detected in ISM/CSMyes


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