Excitation of nitrogen molecular ions in a strong laser field by electron recollisions

A semiclassical model of electron rescattering in a strong laser field is applied to the evaluation of the probability of nitrogen molecular ion excitation. Depending on the ionization phase, a group of electrons oscillate around the parent ion for several laser periods and rescatter at large angles. The effect of ion attraction enhances significantly the probability of ion excitation by electron–ion collisions. The total probability of ion transfer from ground to excited ionic molecular state and the corresponding dipolar moment are evaluated for typical laser filament parameters