The ATI features are clear signatures of MPI processes. The photoelectron-photoion covariance (PEPICOV) analysis revealed that the disentangled PES corresponding to all the ionic fragments look very similar and resemble the PES of the whole system, with the same set of ATI peaks (see dashed PEPICOV lines in Figure ). This indicates that the MPI regime dominates TI in producing low-charge parent ions and fragments. The similarity of the PEPICOV features for the FLU monocation (m/z = 166) and dication (m/z = 83) probably points to the photoionization proceeding sequentially, i.e., first, monocations are produced as FLU + IR → FLU + + e - 1 , where e - 1 is the photoelectron appearing from the first ionization step. Then, the double ionization occurs according to a reaction FLU + + IR → FLU 2+ + e - 2 , where e - 2 is the second ejected electron, which should have a different ATI spectrum. The amount of the monocations in the MS is 4-5 times higher than of the dications, which means that mainly the covariance of FLU 2+ with e - 1 will be visible, as the number of e - 1 will be exceedingly larger than of e - 2 . Additionally, the general mechanism of fragmentation implies obtaining first a highly excited mono-or dicationic state of the parent, which later decays into the charged fragments, thereby providing similar PES. Recoil-frame covariance analysis was performed on the massresolved VMI data to distinguish the various measured fragmentation channels. This approach was shown to be very effective in disentangling the fragmentation pathways of complex PAH molecules. In brief, this method correlates the relative positions of two ions (the reference ion and the ion of interest) on the imaging detector. If the ion of interest is produced simultaneously with the reference ion, we see a recoil feature, a positive covariance in the opposite direction to that defined by the reference ion, which we choose to be upwards. More information on this technique can be found in Ref. 41.