GENERALIZED LOW-FREQUENCY APPROXIMATION FOR SCATTERING IN A LASER FIELD .2.

A time-independent formulation of the problem of scattering in an intense radiation field is used as the basis for a derivation of a low-frequency approximation in which field-free scattering amplitudes enter into the determination of transition amplitudes in the presence of the field. A single-mode field of arbitrary polarization is assumed and the scatterer is represented by a local, short-range potential. In the present derivation the dipole approximation for the field is not assumed. As a result, recoil corrections to earlier versions of the low-frequency approximation are obtained in explicit form. The low-frequency approximation for bremsstrahlung in the absence of a background field, derived some time ago by Low and others, appears as a limiting case of the result obtained here. © 1979 The American Physical Society.