Trihydrogen cation; di-deuterium isotopomer
Species tag 005501
Date of EntryFeb. 2012
ContributorH. S. P. Müller

Both H3+ and D3+ do not have a permanent dipole moment because of symmetry. In contrast, both H2D+ and HD2+ have sizable dipole momenta.
The first entry from April 2004, modified Aug. 2005, has been modified considerably.
The J = 1 – 0 transition of ortho-HD2+ was taken from
(1) O. Asvany, O. Ricken, H. S. P. Müller, M. C. Wiedner, T. F. Giesen, and S. Schlemmer, 2008, Phys. Rev. Lett., 100, Art. No. 233004.
The J = 1 – 1 transition of para-HD2+ was taken from
(2) T. Hirao and T. Amano, 2005, J. Mol. Spectrosc., 233, 7.
One additional transitions of ortho-HD2+ was reported by
(3) D. A. Jennings, C. Demuynck, M. Banek, and K. M. Evenson, private communication in
O. L. Polyansky and A. R. W. McKellar, 1990, J. Chem. Phys., 92, 4039
Infrared ground state combination differences reported in (2) were also used in the fit.
Note: uncertainties of 999.9999 MHz or 0.03336 cm–1 are the largest ones displayed ! All predictions should be viewed with caution because of the small data set.
The ab initio dipole moment was mentioned by
(4) S. C. Foster, A. R. W. McKellar, and J. K. G. Watson, 1986, J. Chem. Phys., 85, 664.
At low temperatures, it may be necessary to discern between ortho-HD2+ and para-HD2+. The ortho and para states are described by Ka + Kc even and odd, respectively. The nuclear spin-weight ratio is 2 : 1 for ortho-HD2+ : para-HD2+. The JKaKc = 111 is the lowest para state. It is 34.9183 cm–1 above ground.
Separate para and ortho predictions are available up to J = 2 and Ka = 2 along with separate para and ortho partition function values. Note: the spin-weight of 2 for the separate ortho predictions has been eliminated.

Lines Listed162
Frequency / GHz< 15426
Max. J11
log STR0-6.0
log STR1-5.3
Isotope Corr.-7.879
Egy / (cm–1)0.0
 µa / D0.486
 µb / D 
 µc / D 
 A / MHz1085400.
 B / MHz654861.
 C / MHz392475.
detected in ISM/CSMyes

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