Laser-induced breakup of helium 3S 1s2s with intermediate doubly excited states

Solving the time-dependent Schrodinger equation in full dimensionality for two electrons, it is found that in the XUV regime the two-photon double ionization dynamics of He(1s2s) is predominantly dictated by the process of resonance enhanced multiphoton ionization via doubly excited states (DESs). We have studied a pump-probe scenario where the full laser-driven breakup of the S-3 1s2s metastable state is dominated by intermediate quasiresonant excitation to doubly excited (autoionizing) states in the P-3(o) series. Clear evidence of multipath interference effects is revealed in the resulting angular distributions of the ejected electrons in cases where more than one intermediate DES is populated in the process.