Efficient sub-Doppler laser cooling of an Indium atomic beam

We have realized efficient transverse cooling of an Indium atomic beam by combining optical pumping with a closed cycle UV laser cooling transition at 325.6 nm. The transverse velocity of the atomic beam is reduced to 13.5 +/- 3.8 cm/s, well below the Doppler cooling limit. The fraction of laser-cooled In atoms is enhanced to 12 +/- 3 % by optical pumping in the present experiment. It can be scaled up to approach 100% efficiency in cooling, providing high brightness atomic beams for further applications. Our results establish In on the map of elements suitable for applications involving laser cooling. (C) 2009 Optical Society of America