Disalignment of excited atoms due to electron and ion collisions

The laser-induced-fluorescence spectroscopy (LIFS) has been applied to a pulsed discharge plasma (2 torr of 95 % helium and 5 % neon mixture gas), and we have observed disalignment of the neon 2p2-level atoms due to electron and ion collisions under the condition of ne = 5.1 x 1013 cm-3 and Te = 2.0 x 103 K. The effect of ion collisions is estimated in the approximation of the static ion microfield. This field causes effective disalignment, and its rate is calculated. The disalignment rate coefficient due to electron collisions is deduced to be (5.3 ± 1.3) x 10-7 cm3 s-1. This rate coefficient is found to be consistent with the Stark width as calculated by Griem. (author)