Observation of laser-assisted electron-atom scattering in femtosecond intense laser fields.

Laser-assisted electron scattering (LAES) in a femtosecond near-infrared intense laser field was observed through the scattering of 1 keV electrons by xenon atoms. The intensities, angular distributions, and laser polarization dependence of the observed LAES signals for the energy gain (+ℏω) and energy loss (-ℏω) processes were interpreted well by numerical simulations. As an application of this femtosecond-LAES process, a new method of time-resolved gas electron diffraction for probing geometrical change of molecules with high precision is proposed.