Double resonance rotational action spectroscopy of cold H2D+ and D2H+

A double resonance action spectroscopic method has been applied to measure low-J rotational transitions of H2D+ and D2H+ up to frequencies of 1.5 THz. The uncertainties of two known lines of H2D+ and three known lines of D2H+ have been improved substantially, and the 2(11) <- 2(12) H2D+ transition measured for the first time. In addition, we derived spectroscopic parameters for both molecular cations using the Euler formalism. (C) 2016 Elsevier Inc. All rights reserved