Motional-Stark-effect-induced anticrossings

Atoms moving through a magnetic field suffer a Stark effect whose magnitude is dependent upon the atom's velocity. This velocity-dependent perturbation has recently been exploited as a Doppler narrowing technique, and in this paper we consider atomic anticrossings induced by it. Experimentally such anticrossings are observed between nD3-nF1,3 states of He for n=4-9, with n=8 being considered in detail. Theoretical expressions are derived for motional-Stark-effect- induced anticrossing line shapes. Good agreement with the observed line shapes is obtained and the theoretical analysis allows a value of the n=D3-F1,3 interval to be obtained which is in good agreement with previous predictions.