A Stark velocity filter for studying cold polar molecule?molecular ion reactions

A Stark velocity filter has been developed for studying molecular ion-polar molecule reactions at very low temperatures. We have successfully produced slow polar molecules of ND3, NH3 and CH2O with a peak velocity of lower than 40 m/s. The property of the Stark velocity filter was systematically studied by changing the Stark voltage, the nozzle pressure and the source gas temperature. Finally the number density of the extracted slow molecules was determined.