Understanding the high-resolution spectral signatures of Ar-D ₂ O in the 3OD stretch region measured by cavity ringdown absorption spectroscopy

We report observation of the weakly-bound Ar-D2O complex in the 3OD overtone stretch region (7900 cm-1). The measurement was made using the FANTASIO cavity ring-down spectrometer (CRDS) combined with a 8 cm long pulsed slit nozzle valve. Several sub-bands are assigned. At 7892 cm-1, the Σ(000), (201) ← Σ(101), (000) band (para nuclear spin species) experiences a moderate (0.04 cm-1) perturbation between J = 6 and 7. At 7903 cm-1, the Σ(101), (201) ← Σ(000), (000) band (ortho nuclear spin species) exhibits a more complicated perturbation at about the same J-values. Most of the observed transitions (187) can be rotationally assigned. Finally, in the range 7913 – 7916 cm-1, the Π (101), (201) ← Σ(000), (000) and Π(110), (201) ← Σ(000), (000) bands (ortho nuclear spin species) are observed, and their rotational analysis remains tentative.