Memories of excited femtoseconds: effects of core–hole localization after Auger decay in the fragmentation of ozone

We present the first photoelectron–photoion–photoion coincidence (PEPIPICO) spectra of ozone, O3, excited at the O1s edge. From symmetry considerations the oxygen atoms at the end of the V-shaped molecule are chemically in-equivalent to the central oxygen atom. For the excitation from one of the terminal O1s orbitals to 7a1(σ∗), experiments combined with simulations yielded that photo-induced breaking of the bond closest to the core-excited terminal atom occurs in at least 70±10% of the cases. We interpret this as due to a `memoryʹ effect of the localized core–hole after the Auger decay. Consequently the sequential two-step model, i.e. core excitation-and-decay resulting in a state with delocalized valence holes followed by dissociation, is not adequate in this case.