Observation of the Q(3/2) Λ-doublet transitions for X²Π₃⁄₂ OD in helium nanodroplets

Abstract

The deuteroxyl radical (OD) has been isolated in superfluid helium nanodroplets and characterised by infrared depletion spectroscopy. Two resolved Q(3/2) lines are observed, with a separation that is 4.88 (10) times larger than in the gas phase. This is similar to that previously reported for He-solvated OH (5.30 (2)), for which it was shown that the splitting could be reproduced by a model that assumes a small parity dependence of the rotor's effective moment of inertia [P.L. Raston, T. Liang, and G.E. Douberly, J. Phys. Chem. A (2013). DOI:10.1021/jp312335q]. With this model, the OD Λ-doublet splitting in liquid He is reproduced with Be and Bf rotational constants that differ by ≈0.24%.