Two-photon double photoionization of atomic Mg by ultrashort pulses*

We investigate the two-photon double ionization of atomic magnesium induced by ultrashort pulses. Much like for beryllium, and in contrast to helium, the range of photon energies for which nonsequential ionization is the only open pathway is very narrow (less than 1~eV). Thus, sequential ionization pathways feature heavily in these processes. The greater significance of excited-state correlating configurations in representing the initial state of magnesium has consequences on the resulting angular distributions at photon energies where sequential ionization can access intermediate states that lie nearby in energy, particularly when the pulse length is increased.