High-resolution inner-shell coincidence spectroscopy

The present review article gives a historical overview of high-resolution inner-shell coincidence spectroscopies followed by selected examples showing their scientific impact in studying molecular fragmentation dynamics. The development of such spectroscopies was intimately related to the last 20 years spectacular advances of the instrumentation. They include the construction of high-performance soft X-ray beamlines at the newest synchrotron radiation facilities, but also the remarkable improvement of charged particles analyzers and detectors and the extensive use of multidimensional coincidence techniques allowing for simultaneous recording and further correlation of several physical parameters. From the examples shown, it clearly appears the importance of using coincidence measurements in addition to pure electron spectroscopy methods in order to fully characterize the complex decay processes of inner-shell excited species leading for instance to site-selective fragmentation, vibrational motion mediated dissociation or ultrafast intramolecular recombination processes. The perspectives of the field will be briefly drawn in the end.