In this paper we study the emergence of two-electron wave packets following the two-photon ionization of
helium with intense near-femtosecond pulses. Monitoring the dynamics of the doubly ionized portion of the
joint radial and energy distributions during the pulse’s lifetime, we observe and examine the effects of strong
Coulombic interactions which take place between electrons with partial waves other than the dominant pp
channels. The generated doubly ionized wave packets correspond to configurations where the two electrons
remain close to the core and roughly equidistant until the pulse’s peak; it is at later times that the sequential or
nonsequential nature of the double-ionization process leads to distinctly different patterns. Moreover, we also
show the difference in the evolution into the corresponding final-state distributions as the pulse’s central photon
energy varies between 42 and 70 eV and, thus, as the ionization mechanism transforms from the so-called
nonsequential to the sequential ionization regime, respectively.