  Rescattering effects in nonresonant spontaneous laser-assisted electron-atom
bremsstrahlung (LABrS) are analyzed within the framework of time-dependent
effective-range (TDER) theory. It is shown that high energy LABrS spectra
exhibit rescattering plateau structures that are similar to those that are
well-known in strong field laser-induced processes as well as those that have
been predicted theoretically in laser-assisted collision processes. In the
limit of a low-frequency laser field, an analytic description of LABrS is
obtained from a rigorous quantum analysis of the exact TDER results for the
LABrS amplitude. This amplitude is represented as a sum of factorized terms
involving three factors, each having a clear physical meaning. The first two
factors are the exact field-free amplitudes for electron-atom bremsstrahlung
and for electron-atom scattering, and the third factor describes free electron
motion in the laser field along a closed trajectory between the first
(scattering) and second (rescattering) collision events. Finally, a
generalization of these TDER results to the case of LABrS in a Coulomb field is
discussed.
