Velocity distribution of the pulsed ND3 molecular beam selected by a quadrupole Stark velocity filter

Slow ND3 molecules are selected from Maxwell-Boltzmann distribution at room temperature by using a pulsed nozzle and a Stark filter. The velocity distribution after the filter is derived (dots) from TOF measurement, and agrees well with a simulation based on Stark effects on all the rotational states (red). For example, the contribution from a single rotational state is shown (blue). The slowest component detected is equivalent to T = 4 K of the thermal energy.