Static-Electric-Field-Induced, High-Energy Plateau for Scattered X-Ray Photons in Laser-Assisted, X-Ray–Atom Scattering

We consider scattering of x rays by H atoms in the presence of both a linearly polarized laser field and a static electric field. Results for the differential cross section as a function of the number of photons n exchanged with the laser field are presented. For x-ray--atom scattering in the presence of a 10¹⁴W/cm² laser field the differential cross section has a plateau only for emitted photons ( $n<0$). Adding a static electric field gives rise to an extended plateau for absorbed photons ( $n>0$), indicating a substantial increase of the scattered x-ray energies. We present a quasiclassical explanation of these results.