RYDBERG ATOMS IN TIME-DEPENDENT ELECTRIC-FIELDS

An approximate representation of atomic states in a rapidly varying time-dependent electric field F(t) is presented, and its range of validity is explicitly determined. The approximation is tested for different time-dependent forms of F(t) by comparing with exact numerical solutions, where the field induced mixing is treated by including spherical hydrogenic states up to n less-than-or-equal-to 25 in the coupled equations. Within this validity range, the proposed formula describes the field dressed atomic wave functions surprisingly well, and improves with increasing principal quantum number of initial states. The formula has a wide range of applicability, and may be used to treat the effects of fluctuating plasma dipole fields and externally imposed oscillating electric fields on atomic transitions.