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, O-3, excited at the O1s edge. From symmetry consideratio ns the oxygen atoms at the end of the V-shaped molecule are chemically in-e quivalent to the central oxygen atom. For the excitation from one of the te rminal O1s orbitals to 7a(1)(sigma *), experiments combined with simulation s yielded that photo-induced breaking of the bond closest to the core-excit ed terminal atom occurs in at least 70 +/- 10% of the cases. We interpret t his as due to a 'memory' 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 diss ociation, is not adequate in this case. (C) 2000 Elsevier Science B.V. All rights reserved.