Semiclassical theory of molecular nonsequential double ionization

Abstract

A semiclassical molecular nonsequential double ionization theory is developed based on the rescattering model. We show that, in the nonsequential double ionization of D{sub 2}, the kinetic energy of the returning electron changes from below to above the ionization threshold of the parent ion as the laser varies from short to long wavelength, resulting in the dominance of collisional ionization at shorter laser wavelength and field ionization at longer laser wavelength. We also calculate the double ionization time distribution of D{sub 2} and the kinetic energy distribution of D{sup +}. The theoretical results are qualitatively consistent with experimental measurements. The nonsequential double to single ionization ratio of N{sub 2}{sup 2+}/N{sub 2}{sup +} is also calculated and compared with available experimental results.