High-resolution optical spectroscopy with a buffer-gas-cooled beam of BaH molecules

摘要

Barium monohydride (BaH) is an attractive candidate for extending laser cooling and trapping techniques to diatomic hydrides. The apparatus and high-resolution optical spectroscopy presented here demonstrate progress toward this goal. A cryogenic buffer-gas-cooled molecular beam of BaH was constructed and characterized. Pulsed laser ablation into cryogenic helium buffer gas delivers ~1 × 10~(10) molecules/sr/pulse in the X~2Σ~+(v'' = 0,N'' = 1) state of primary interest. More than 1 × 10~7 of these molecules per pulse enter the downstream science region with forward velocities below 100 m/s and transverse temperature of 0.1 K. This molecular beam enabled high-resolution optical spectra of BaH in quantum states relevant to laser slowing and cooling. The reportedmeasurements include hyperfine structure and magnetic g factors in the X~2Σ~+,B~2Σ~+, and A~2∏_(1/2) states.