Quantum mechanical wavepacket dynamics simulation that includes the nuclear motion exhibit a prompt, few fs, dissociation of electronically attosecond excited N-2 in addition to the slow dissociation evident from spectral line broadening in well resolved spectra. The simulations show that nuclear motion can probe early times electron dynamics. The separation of time scales is mimicked by a model study fashioned like chemical kinetics of unimolecular dissociation. The physical origin of the separation into prompt and delayed decay is argued to be the same in the vibrational and the present case, namely that there are more bound than dissociative channels. (C) 2014 Published by Elsevier B.V.