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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.

International audienceA Doppler-type shift in the kinetic energy of atomic Auger electrons emitted after fast dissociation of O3 molecules is observed. The resonant Auger spectrum from the decay of repulsive core-excited states reflects both the early molecular ozone decay and that from excited dissociation fragments. The kinetic energy of the fragment is manifested as an energy shift of the atomic Auger lines when the measurement is made under certain conditions. We report measurements of the energy-split atomic fragment emission lines arising from dissociation on a time scale comparable to the core-hole lifetime. For the O 1s–* states the kinetic energy release amounts to several electron volts. We report measurements for excitation of both the terminal and central oxygen 1s electrons. A simple kinematic model for extracting a lower limit for the kinetic-energy release is presented and is compared with the result of a Born–Haber cycle, which may be seen as an estimate of the maximum energy releas

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