Stark Deceleration

We have produced beams of cold LiH molecules in the first rotationally excited state, which is a weak-field seeking state. We decelerate these molecules to low velocity using a 100 stage Stark decelerator operated at a field strength of 100kV/cm. The electric field of the decelerator is switched on and off so that the molecules are always moving out of regions of weak field and into regions of strong field. This slows the molecules down, reducing their speed nearly to zero at the exit of the decelerator.

The figure below shows data demonstrating the deceleration of lithium hydride molecules.  The molecules entered the decelerator with a speed of 420m/s. The graphs show the time of flight profiles of the molecules, measured by laser induced fluorescence at the exit of the decelerator, as the degree of deceleration is increased. The decelerated bunch moves to later arrival times as the molecules slow down. The arrows show arrival times predicted from a simple model, with the final speed shown next to each. The slowest molecules we have produced are moving at 53m/s, slow enough to begin trapping experiments.

We have worked on the deceleration of  YbF and CaF molecules, in weak-field and strong-field seeking states.

The figure shows the deceleration of ground state CaF molecules. The molecules enter the decelerator at a speed of 435m/s. The arrival time of the molecules at the detector tells us about their speeds. The figure shows this arrival time, relative to the central arrival time when the decelerator is turned off. A narrow peak appears in the time profiles, which is delayed more and more as the number of deceleration stages used increases. These are the decelerated molecules. 

Most recently, in collaboration with Gerard Meijer's group, we have shown how to decelerate YbF molecules in a travelling wave decelerator.

Ground state molecules can be transported in an alternating gradient guide. The operating principle is the same as for the decelerator. We have demonstrated a guide that has a four-rod geometry designed to minimize the lens aberrations which tend to reduce the transmission. The guide is useful for transporting molecules from a cold source, such as a buffer gas source. 

Traveling wave deceleration of heavy polar molecules in low-field seeking states, N.E. Bulleid, R.J. Hendricks, E.A. Hinds, Samuel A. Meek, Gerard Meijer, Andreas Osterwalder, and M.R. Tarbutt, Phys. Rev. A 86, 021404(R) (2012)

Stark deceleration of CaF molecules in strong- and weak-field seeking states, T. E. Wall, J. F. Kanem, J. M. Dyne, J. J. Hudson, B. E. Sauer, E. A. Hinds and M. R. Tarbutt, Phys. Chem. Chem. Phys. 13, 18991 (2011)

Nonadiabatic Transitions in a Stark Decelerator, T. E. Wall, S.K. Tokunaga, E.A. Hinds, M.R. Tarbutt, Physical Review A 81, 033414 (2010)

Stark deceleration of lithium hydride molecules, S. K. Tokunaga, J. M. Dyne, E. A. Hinds and M. R. Tarbutt, New Journal of  Physics 11, 055038 (2009)

Transport of pol ar molecules by an alternating gradient guide, T.E. Wall, S. Armitage, J.J. Hudson, B.E. Sauer, J.M. Dyne, E.A. Hinds, M.R. Tarbutt, Physical Review A, Vol. 80, 043407, (2009)