Intracavity laser absorption spectroscopy of HDO between 12145 and 13160 cm 1

The high resolution absorption spectrum of monodeuterated water, HDO, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) in the 12145–13160 cm 1 region. The achieved sensitivity (noise equivalent absorption on the order of amin 10 9 cm ) allowed detecting transitions with line strengths as weak as 10 27 cm/molecule which is about 50 times lower than the weakest line intensities previously detected in the considered region. The rovibrational assignment of the 1179 lines attributed to the HDO isotopologue was based on the results of the variational calculations of Schwenke and Partridge as well as the recent calculations based on a new HDO potential energy surface refined from the fitting to the available experimental data. The overall agreement between these new calculations and the observed spectrum is very good, the rms deviation of the differences between the calculated and observed energy values being 0.05 cm . A set of 304 new experimental HDO energy levels was obtained. In particular, band origins for the (122), (202), and (311) vibrational states, at 12568.190, 12644.652, and 12919.938 cm , respectively, and their rotational sublevels are derived for the first time. A detailed HDO database of 1337 transitions was constructed and is provided as Supplementary Material. 2007 Elsevier Inc. All rights reserved.