Eur. Phys. J. D 40, 73-80 (2006)
https://doi.org/10.1140/epjd/e2006-00095-1

Measurement of the three-dimensional velocity distribution of Stark-decelerated Rydberg atoms

Laboratorium für Physikalische Chemie, ETH Zurich, HCI Hönggerberg, 8093 Zurich, Switzerland

Corresponding author: ^a frederic.merkt@ethz.ch

Received: 1 December 2005
Revised: 14 February 2006
Published online: 28 April 2006

Abstract

The full three-dimensional velocity distributions of decelerated and accelerated particles in a Stark decelerator for Rydberg atoms and molecules have been measured. In the experiment, argon atoms in a supersonic beam are excited to low-field and high-field seeking Stark states with principal quantum number in the range n=15 to 25 and are decelerated in a 3 mm long decelerator consisting of four electrodes on which time-dependent voltages are applied. The time dependence of the resulting inhomogeneous electric field is chosen such that the decelerating force acting on the high-field seeking states is maximized at each point along the trajectories. The three-dimensional velocity distribution of the atoms before and after the deceleration is determined by measuring times of flight and two-dimensional images of the atomic cloud on the detector. Under optimal deceleration conditions, the decrease in kinetic energy in the longitudinal dimension amounts to 1.0×10^-21 J and the increase in mean kinetic energy in the transverse dimensions is only 1.0×10^-23 J. The corresponding temperatures of 100 mK and 300 mK in the two transverse dimensions are sufficiently low that trapping can be envisaged. The possibility of focusing a Rydberg atom beam is demonstrated experimentally.