Electron diffraction patterns from laser illuminated crystals

Recent experiments in which a crystal was exposed to an electron beam and laser light are treated here by quantum mechanical scattering theory. Diffraction patterns oscillating with the laser frequency are predicted in agreement with experimental results. Three effects are considered: (i) scattering due to laser induced crystal oscillations; (ii) scattering from the crystal with subsequent deflection by the laser field; (iii) the inverse of (ii). The latter two processes seem to be dominant. Periodic modulation of the intensity with increasing distance to the screen is predicted.