Momentum distribution of highly charged ions formed by strong laser fields

Momentum distributions of highly charged ions produced by a strong laser pulse with duration of ~ 200 fs and maximum intensity of ~50-70 PW/cm2 are studied. Due to the spatial variation of the laser intensity within the beam focus, different charge states are produced during a single laser shot. The measured widths of the momentum distribution of the product ions exhibit a linear dependence on the ionization potential of the ions for various rare gas atoms. Such a linear dependence is analyzed theoretically using the single active electron model.