Double ionization of H2 by intense attosecond laser pulses

We present calculations of the double ionization of H2 induced by an intense attosecond laser pulse at a photon energy of 40 eV using the time-dependent close-coupling method within the fixed nuclei approximation. We focus on two-photon absorption processes and examine how the response of the ejected electrons, in particular the singleand the double-energy differential probabilities, is affected by linear and circular polarizations at laser-field intensities ranging from 1015 W cm−2 to 1016 W cm−2. In general, we find that for both linearly and circularly polarized pulses, sequential peaks and non-sequential wells that appear in both the singleand double-energy differential probabilities are akin to the analogous two-electron photoemission processes in the helium atom driven by intense attosecond pulses. In addition, for the case of a linearly polarized pulse, a clear signature of the sequential double-electron above the threshold ionization process can be seen in these spectra. (Some figures in this article are in colour only in the electronic version)