Intracavity laser absorption spectroscopy of D2O between 11 400 and 11 900 cm

The weak absorption spectrum of dideuterated water, D₂O, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) between 11 400 and 11 900 cm⁻¹. This spectrum is dominated by the 3ν₁ + ν₂ + ν₃ and the ν₁ + ν₂ + 3ν₃ centered at 11 500.25 and 11 816.64 cm⁻¹, respectively. A total of 530 energy levels belonging to eight vibrational states were determined. The rovibrational assignment process of the 840 lines attributed to D₂O was mostly based on the results of new variational calculations consisting in a refinement of the potential energy surface of Shirin et al. [J. Chem. Phys., 120 (2004) 206] on the basis of recent experimental observations, and a dipole moment surface from Schwenke and Partridge [J. Chem. Phys. 113 (2000) 6592]. The overall agreement between these calculations and the observed spectrum is very good both for the line positions and the line intensities.