Correlated multiphoton double ionization of helium: The role of non-adiabatic tunneling and singlet recollision

We study the role of singlet coupling during double ionization of Helium atoms in intense laser fields, within the framework of the recollision model. The singlet cross sections for inelastic e+He+ scattering, integrated over all excitation and ionization channels, are used. Nonadiabatic corrections during tunneling of the active electron are also included.Peer reviewed: YesNRC publication: Ye