Effects of intense magnetic and motional Stark fields on state mixing and transition line shapes

Abstract

The theoretical treatment of the combined effects of strong magnetic and motional electric fields on a simple atom, such as ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, is developed. It is shown that normal selection rules are relaxed by the external fields and that many previously forbidden transitions become allowed. The transition moment is shown to be velocity dependent, resulting in new and unique line shapes for these transitions. The theory is presented in a form directly applicable to the experiments reported in the accompanying paper.