Non-adiabatic 2s-2p state mixing in metastable hydrogen by electric fields

The evolution of a (/b n/=2) hydrogen atom passing through a linearly increasing or decreasing electric field is calculated in a three-state approximation. The observable fraction of 2p/sub 1/2/, 2s/sub 1/2/ and 2p/sub 3/2/ quantum state in the resulting coherent mixture is calculated. The amplitude of the oscillations, which appear when the field parameters are varied, is shown to depend only on the rate of change of the field, as seen by the atom. Maps of oscillation amplitudes and average values are given for the metastable atom. Comparison is made with the sudden and adiabatic approximations.Anglai