Pathways to non-sequential multiple ionization in strong laser fields

Abstract

The outgoing electrons in non-sequential multiple ionization in intense laser fields arestrongly correlated. The correlations can be explained within a classical model forinteracting electrons in the presence of the external field. Here we extend the previousanalysis for two and three electrons to cases with up to eight electrons and identify thesaddle configurations that guard the channels for non-sequential multiple ionization. Forfour and fewer electrons, the electrons in the dominant configuration are equivalent; for sixand more electrons this is no longer the case. The case of five electrons is marginal, withtwo almost degenerate transition configurations. The total number of configurationsincreases rapidly, from two configurations for three electrons up to 26 configurations foreight electrons.