The observed transition frequencies have been published by
(1) S. Brünken, H. S. P. Müller, K. M. Menten, M. C. McCarthy, and P. Thaddeus, 2008, Astrophys. J., 676, 1367.
With respect to the Apr. 2008 entry, additional millimeter wave data were included. These were published by
(2) P. Kania, M. Hermanns, S. Brünken, H. S. P. Müller, and T. F. Giesen, 2011, J. Mol. Spectrosc., 268, 173.
Data of three isotopic species, ⁴⁸TiO₂, ⁴⁶TiO₂, and ⁵⁰TiO₂, have been fit together as described in (1) and (2). Predictions with uncertainties larger than 1 MHz should be viewed with caution.
An experimental dipole moment was determined in
(3) H. Wang, T. C. Steimle, C. Apetrei, J. P. Maier, 2009, Phys. Chem. Chem. Phys., 11, 2649.