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ABSTRACT
Deceleration of supersonic beams of SD radicals by a linear Stark decelerator was demonstrated for the first time. SD radicals produced by an electric discharge of supersonic beams mainly occupied the lowest two rotational states of and
in the 2Π3/2 state. Laser-induced fluorescence of the decelerated beam showed that, due to the proximity of the Stark shift between these two rotational states, the final radical packet still contained both the
and
rotational states when the decelerator was operated at a constant phase below 50°. We show that by controlling the timing sequence of the Stark decelerator, it is possible to create a decelerated molecular packet containing only a single rotational state of either
or
of the SD radicals with a tunable velocity. The creation of a cold radical beam containing a single rotation–vibration state will be a useful tool for the study of cold collisions and reactions in the quantum regime.
Acknowledgements
We acknowledge Sajjad Haidar, Chris Bedford, and Adam Schonewille at UBC for their technical support.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
1. The voltage of ±125 V, corresponding to the field strength of 161 kV m−1, was designed to avoid non-adiabatic transitions for the deceleration of NH3. For SD radicals, this bias voltage can be smaller because of the smaller difference in Stark shifts in different quantum levels than NH3 [Citation28]. However, we kept this ±125 V bias voltage for the present study to make the electronics design of our decelerator simple.