High‐resolution Inner‐shell Photoionization, Photoelectron and Coincidence Spectroscopy

Abstract

This article gives an overview of high‐resolution photoionization, photoelectron, and coincidence spectroscopies of inner‐shell excited species of increasing complexity ranging from atoms to nanoparticles. The development and the routine use of soft X‐ray techniques is intimately related to the spectacular advances in instrumentation in the last twenty years. These concern not only the construction and operation of high‐performance soft X‐ray beamlines at several synchrotron radiation laboratories around the world but also the remarkable improvement in charged particle analyzers and detectors (detection efficiency, resolution) and the extensive use of multidimensional coincidence techniques that allows simultaneous acquisition and further correlation of several physical parameters. From the examples we have chosen to present, it is apparent that inner‐shell ionization studies are not limited anymore by the lifetime broadening effects and that a deep and unique insight into ultrafast dynamics is possible. Various examples are shown of both pure high‐resolution photoionization and electron spectroscopies together with more sophisticated techniques such as the electron–ion coincidence measurements with energy and angle resolution. A prospective view of the field is given in the end. In particular, the expectations from the next‐generation ultrahigh brilliance X‐ray sources such as energy recovery linacs or free electron lasers are briefly tackled.

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