The role of Volkov waves in laser-assisted electron momentum spectroscopy

► Theory of laser-assisted electron-impact ionization of atomic hydrogen. ► Nd:YAG laser with intensity of 4 TW/cm2. ► Time-dependent perturbation theory for field-dressed atomic hydrogen. ► Volkov waves for incoming and outgoing electrons with energies of 1-2 keV. ► Volkov-wave effects dramatically influence laser-assisted momentum profiles.