Time-resolved mapping of correlated electron emission from helium atom in an intense laser pulse

We apply and analyze the concept of mapping ionization time on to the final momentum distribution to the correlated electron dynamics in the nonsequential double ionization of helium in a strong laser pulse (lambda = 800 nm) and show how the mapping provides insight into the double ionization dynamics. To this end, we study, by means of numerical integration of the time-dependent Schrodinger equation of a fully correlated model atom, the temporal evolution of the center-of-mass momentum in a short laser pulse. Our results show that in the high intensity regime (I-0 = 1.15 x 10(15) W cm(-2)), the mapping is in good agreement with a classical model including binary and recoil rescattering mechanisms. In the medium intensity regime (I-0 = 5 x 10(14) W cm(-2)), we identify additional contributions from the recollision-induced excitation of the ion followed by subsequent field ionization (RESI).