Electromagnetic transitions between Rydberg states of a hydrogen atom: Violation of the dipole selection rules in a strong field

One-quantum bound-bound transitions between high-excited states of a hydrogen atom are considered. Electron wave functions involving an electromagnetic field even in a zero-order approximation are constructed semiclassically. With these functions, it is shown that transitions accompanied by violation of the dipole selection rules are possible in strong fields. The probability of such transitions is a nonlinear function of electromagnetic field intensity. (C) 2000 MAIK "Nauka/Interperiodica".