Trihydrogen cation; mono-deuterium isotopolog
Species tag 004501
Date of EntryMar. 2017
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 Aug. 2005 has been revised considerably, and so has the second one from Feb. 2012. The fitting method, including the derivation of initial spectroscopic parameters from quantum chemical calculations, has been described by
(1) P. Jusko, M. Töpfer, H. S. P. Müller, P. N. Ghosh, S. Schlemmer, and O. Asvany, 2017, J. Mol. Spectrosc., 332, 33.
In addition to extensive remeasurements and one new transition frequency, earlier data were scritinized. Additional data were taken from
(2) 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;
(3) P. Jusko, C. Konietzko, S. Schlemmer, and O. Asvany, 2016, J. Mol. Spectrosc., 319, 55;
(4) T. Amano, 2006, Phil. Trans. R. Soc. A, 364, 2943;
(5) T. Yonezu, F. Matsushima, Y. Moriwaki, K. Takagi, and T. Amano, 2009, J. Mol. Spectrosc., 256, 238;
(6) S. Saito, K. Kawaguchi, and E. Hirota, 1985, J. Chem. Phys., 82, 45;
and from
(7) T. Amano and T. Hirao, 2005, J. Mol. Spectrosc., 233, 7.
Infrared ground state combination differences reported in (7) were also used in the fit.
Predictions should be reliable if J ≤ 4 and Ka ≤ 2, possibly higher. The largest uncertainties shown are 999.9999 MHz.
At low temperatures, it may be necessary to discern between ortho-HD2+ and para-HD2+. The ortho and para states are described by Ka = odd and even, respectively. The nuclear spin-weight ratio is 3 : 1 for ortho-HD2+ : para-HD2+. The JKaKc = 111 is the lowest ortho state. It is 60.0292 cm–1 above ground.
Separate para and ortho predictions are available up to J = 4 and Ka = 3 along with separate para and ortho partition function values.
The dipole moment was estimated in
(8) A. Dalgarno, E. Herbst, S. Novick, and W. Klemperer, 1973, Astrophys. J., 183, L131.

Lines Listed196
Frequency / GHz< 20000
Max. J12
log STR0-8.0
log STR1-6.5
Isotope Corr.-3.939
Egy / (cm–1)0.0
 µa / D0.6
 µb / D 
 µc / D 
 A / MHz1302313.
 B / MHz873595.
 C / MHz497737.
detected in ISM/CSMyes

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