Volume 83, Number 2, July 2008
Article Number 23001
Number of page(s) 5
Section Atomic, Molecular and Optical Physics
Published online 05 July 2008
EPL, 83 (2008) 23001
DOI: 10.1209/0295-5075/83/23001

Mechanical effect of photoassociation for ultracold metastable helium atoms: A new method to measure the scattering length

S. Moal, M. Portier, J. Kim, E. Arimondo and M. Leduc

École Normale Supérieure, Laboratoire Kastler Brossel - 24 rue Lhomond, 75231 Paris Cedex 05, France, EU

received 14 January 2008; accepted in final form 30 May 2008; published July 2008
published online 5 July 2008

We report a new method to detect photoassociation (PA) resonance signals through the collective dipole oscillations produced by a momentum transfer from the PA excitation lasers to an ultracold atomic cloud confined by a magnetic trap. Using the amplitudes of these oscillations for several molecular excited states, we derive a precise value for the s-wave scattering length between the ultracold atoms. This new and simple method provides results in excellent agreement with previous spectroscopic PA measurements based on atom losses or temperature rise. We present a simple model interpreting the momentum and energy transferred from the PA process to trap confined ultracold atoms.

37.10.Vz - Mechanical effects of light on atoms, molecules, and ions.
33.20.-t - Molecular spectra.
67.25.-k - 4He.

© EPLA 2008