Direct observation of Ba+velocity distributions in a drift tube using singlehyphen;frequency laserhyphen;induced fluorescence

摘要

First results are presented on velocity distribution measurements of Ba+ions drifted in helium using a wellhyphen;characterized drift tube and singlehyphen;frequency laserhyphen;induced fluorescence detection. Reduced mobilities of Ba+in helium are obtained forE/Nvalues between 7.74 and 23.2 Td. The velocity distributions that are observed parallel to the electric field fit a displaced Maxwellndash;Boltzmann distribution, in agreement with theoretical predictions. However, the temperatures parallel and perpendicular to the field are not in good agreement with theoretical treatments.