Spectroscopy of laser cooling transitions in MgF

We measure the complete set of transition frequencies necessary to laser cool and trap MgF molecules. Specifically, we report the frequency of multiple low J transitions of the X²Σ⁺(v^=0,1) → A²Π1/2(v⁼0), X²Σ⁺(v^=1,2) → A²Π1/2(v⁼1), and X²Σ⁺(v^=1) → B²Σ⁺(v^=0) bands of MgF. The measured X²Σ⁺(v^=1)→ B²Σ⁺(v⁼0) spectrum allowed the spin-rotation and hyperfine parameters of the B²Σ⁺(v=0) state of MgF to be determined. Furthermore, we demonstrate optical cycling in MgF by pumping molecules into the X²Σ⁺(v=1,2) states. Optical pumping enhances the spectroscopic signals of transitions originating in the N^=1 level of the X²Σ⁺(v^=1,2) states.