Perturbation spectroscopy of the He-Cd laser discharge

Chopping the radiation field in the cavity of a helium-cadmium laser operating at 4416 AA induces perturbations in the populations of the 5s 2 2 D 3/2,5/2 and 5p 2 P 3/2 levels of Cd II. Analysis of the perturbations of the 5p 2 P 3/2 and 5s 2 2 D 5/2 populations shows that the ratio of non-radiative to radiative de-excitation rates for the upper laser level is 0.9+or-0.2, approximately independent of discharge conditions. From the population changes of the 5s 2 2 D 3/2 level the cross section for excitation from the 5s 2 2 D 5/2 level by electron collisions is found be be approximately 7*10 -16 cm 2 and the ratio of this cross section to that for excitation from the 5p 2 P 3/2 level is 10 -3 .