Associative ionisation of laser excited sodium in an atomic beam

Abstract
The authors have observed ion formation when a non-velocity-selected atomic sodium beam is irradiated with a CW dye laser tuned to one of the D-lines. The ions are formed by associative ionisation according to Na(3P)+Na(3P) to Na2++e, with an effective cross section of about 5*10-18 cm2 at a mean relative kinetic energy of 0.007 eV.