Laser-modified electron bremsstrahlung in a Coulomb field - art. no. 033406

We study spontaneous emission of electromagnetic radiation by an electron w ith given initial asymptotic momentum in interaction with a Coulomb field a nd with a homogeneous monochromatic electric field (laser field in dipole a pproximation). The intense field effects are taken into consideration for t he initial and final continuum electron states, by using improved Volkov-Co ulomb wave functions, including second-order corrections in the interaction with the electromagnetic field. For the evaluation of the transition ampli tudes, the so-called three-delta approximation introduced by Korol [A. V. K orol, J. Phys. B 28, 3873 (1995)] is adopted. The numerical results are pre sented for a linearly polarized field of frequency of 0.117 eV, intensities up to 10(-6) a.u., electron energies in the range 50-500 eV, and incident momentum orthogonal to the laser polarization direction. The study focuses on spontaneous emission accompanied by exchange of a fixed number n=0, +/-1 ,+/-2 of photons with the external field. Deviations from Born results are shown in several cases. We illustrate in graphs how the spontaneous emissio n is drastically reduced by the presence of the external field.