  In strong field ionization, the pump pulse not only photoionizes the
molecule, but also drives efficient population exchanges between its ionic
ground and excited states.In this study, we investigated the population
dynamics accompanying strong field molecular photoionization, using angular
distribution of dissociative fragments after ionization.Our results reveal that
the first and higher order processes of the post-ionization population
redistribution mechanism (PPRM) in the ion core can be disentangled and
classified by {its} angle-resolved kinetic energy release (KER) spectra.We
demonstrate that the imprints of PPRM in the KER spectra can be used to
determine the branching ratio of the population exchange pathways of different
orders, by exploiting the pump intensity dependent variation of the spectra.
