  In this work, we apply the Monte Carlo wave packet method to study the
ultrafast nuclear dynamics following inner-shell photoionization of N2 exposed
to an ultrashort intense X-ray pulse. The photon energy of the X-ray pulse is
large enough to remove a 1s electron from the N atom in N2. The intermediate
state in N+2 is highly excited so that autoionization takes place from this
state to the dissociative or non-dissociative electronic states of ungerade and
gerade symmetries in N++2. The possible vibrational resonances allowed by the
non-dissociative states prevents a direct extraction of the nuclear kinetic
release (KER) spectrum from the nuclear wave packets in N++2. Therefore, we
propose a hybrid technique by combining the advantages of two energy analysis
strategies to obtain the final nuclear KER spectrum of the process. A
femtosecond IR probe pulse, which couples the electronic states in N++2
together, is applied to achieve a time-resolved imaging and controlling of the
ultrafast dynamics that takes place during double ionization of N2. The
influence of the laser parameters including the peak intensity, pulse duration
and pump-probe delay, on the nuclear dynamics is also investigated.
