Laser slowing of CaF molecules to near the capture velocity of a molecular MOT

Laser slowing of CaF molecules down to the capture velocity of a magneto-optical trap for molecules is achieved. Starting from a two-stage buffer gas beam source, we apply frequency-broadened ‘white-light’ slowing and observe approximately 6 × 10 4 CaF molecules in a single pulse with velocities 10 ± 4 m s −1 . CaF is a candidate for collisional studies in the mK regime. This work represents a significant step towards magneto-optical trapping of CaF.