Molecular tunnelling ionization and rescattering induced double ionization of H2 and D2 molecules

We review the recently developed molecular tunnelling ionization theory, which is an extension of the well-known tunnelling model for atoms, by taking into account the characteristic of molecular orbitals. Employing the molecular tunnelling theory and the rescattering model, we have studied the double ionization of D2 and H2 molecules by intense lasers. Comparing our calculated kinetic energy release spectra of D+ with the measured data, we can derive the time duration between the first and second ionizations to sub-femtosecond accuracy and the breakup distance of D2 to within a fraction of one Angstrom.