Ion momentum distributions for He single and double ionization in strong laser fields

Using a semiclassical rescattering model, the momentum distributions of recoil ions from laser induced single and double ionization are obtained. Not only in the case of double ionization but also in the case of single ionization, the distributions of the momentum parallel to the polarization direction of the laser field show a double-hump structure as a consequence of the rescattering. By comparing with experimental data we find that, as the intensity of the laser decreases, the rescattering ionization mechanism of the second electron as calculated within our model does not dominate the process. In addition, the correlated emission of the electrons in the double ionization is discussed and the effect of the repulsion between the emitted electrons is shown.