State purified deceleration of SD radicals by a Stark decelerator

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 ²Π_3/2 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.

Keywords:

• cold molecules
• Stark deceleration
• SD radicals
• cold collisions

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 [28]. However, we kept this ±125 V bias voltage for the present study to make the electronics design of our decelerator simple.

Additional information

Funding

This work was supported by an NSERC Discovery Grant [RGPIN-2015-06014] and funds from Canada Foundation for Innovation (CFI) to the Centre for Research on Ultra Cold Systems (CRUCS) at UBC [LEF/NIF 2009, #21591]. D. Carty and E. Wrede would like to acknowledge the support of the EPSRC Programme Grant ‘MMQA: MicroKelvin Molecules in a Quantum Array’ [EP/I012044/1].