Deceleration of a Supersonic Beam of SrF Molecules to 120 m s−1

A beam of SrF molecules is decelerated from 290 to 120 m s−1. Following supersonic expansion, the molecules in the X2Σ (ν=0, N=1) low‐field‐seeking state are trapped by the moving potential wells of a traveling‐wave Stark decelerator. With a deceleration strength of 9.6 km s−2 the removal of 85 % of the initial kinetic energy in a 4 m‐long modular decelerator is demonstrated. The absolute amount of kinetic energy removed is a factor of 1.5 higher compared to previous Stark‐deceleration experiments. The demonstrated decelerator provides a novel tool for the creation of highly collimated and slow beams of heavy diatomic molecules, which serve as a good starting point for high‐precision tests of fundamental physics.