Rescattering Double Ionization ofD2andH2by Intense Laser Pulses

Abstract

We have measured momentum spectra and branching ratios of charged ionic fragments emitted in the double ionization of ${\mathrm{D}}_2$ (and ${\mathrm{H}}_2$) molecules by short intense laser pulses. We find high-energy coincident ${\mathrm{D}}^{+}$ (and ${\mathrm{H}}^{+}$) ion pairs with kinetic energy releases between 8 and 19 eV which appear for linearly polarized light but are absent for circularly polarized light. The dependence on the polarization, the energy distributions of the ions, and the dependence on laser intensity of yield ratios lead us to interpret these ion pairs as due to a rescattering mechanism for the double ionization. A quantitative model is presented which accounts for the major features of the data.