Observation of associative ionization of ultracold laser-trapped sodium atoms

Abstract

We have observed associative ionization of laser-cooled and -trapped sodium atoms. The measured rate coefficient for the process at a temperature of 0.75\ifmmode\pm\else\textpm\fi{}0.25 mK is (1.1${\ifmmode\pm\else\textpm\fi{}}_{0.5}^{1.3}$)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, which implies a cross section of 8.6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}14}$ ${\mathrm{cm}}^{2}$. This is 3 orders of magnitude larger than the cross section measured in previous experiments at higher temperatures. The measurement involves the use of a new kind of laser trap.