Laser-assisted Auger decay as free-free transitions in a high-intensity laser field

We investigate the effect of an intense optical field on the energies of electrons ejected in an Auger process. To this end, part of a subpicosecond, infrared laser beam is focused onto a metal target to produce subpicosecond, broadband x radiation. Electrons resulting from the x-ray-induced LMM Auger transition in argon are detected in a time-of-flight electron spectrometer. The other part of the infrared laser beam is directly focused onto the argon atoms. When the x-ray-induced Auger transition takes place in the presence of the intense dressing beam, sidebands appear around the Auger peaks in the electron spectrum, corresponding to absorption or emission of photons from the dressing field. The magnitude of the sidebands is studied as a function of dressing field intensity. Good quantitative agreement with quantum-mechanical theory is reported.