Optical Stark spectroscopy of the (0 0 0) ← (0 0 0) system of barium monohydroxide, BaOH

The A ˜ 2 Π r (0 0 0) ← X ˜ 2 Σ + (0 0 0) system of a cold beam of barium hydroxide, BaOH, has been studied field-free and in the presence of a static electric field. Stark tuning of the low-J branch features in the A ˜ 2 Π 3 / 2 (0 0 0) ← X ˜ 2 Σ + (0 0 0) transition were analyzed to give permanent electric dipole moments, μ, for the A ˜ 2 Π 3 / 2 (0 0 0) and X ˜ 2 Σ + (0 0 0) states of 0.477(7) D and 1.43(4) D, respectively. The results are compared with other alkaline earth monohydroxides and values predicted using an electrostatic polarization model and ligand field theory.