Doppler splitting of In-flight auger decay of dissociating oxygen molecules: the localization of delocalized core holes

By exploiting the core-excitation-induced dissociation of O2, we find that the Auger emission exhibits a Doppler-like energy shift. We show this to be a manifestation of localization of the core hole and propose that the problem of core-hole localization versus delocalization in core-hole spectroscopies may be resolved by considering the nature of the measurement.