The interpretation and application of two-dimensional photoelectron spectroscopy

The technique of two-dimensional photoelectron spectroscopy, in which photoelectron yield is measured as a function of both electron and photon energy, is explained. The appearance of autoionising resonance features is modelled under a variety of experimental conditions. Although two-dimensional spectra normally provide a large amount of detailed information, it is often necessary to extract one-dimensional spectra in order to perform comparisons with other work. The extraction procedure is considered using the specific example of constant transition energy spectra, which indicate the population of particular ion states as a function of photon energy. In addition, experimental effects that are readily visible in two-dimensional spectra, but which may be hard to identify in one-dimensional measurements, are highlighted. Representative two-dimensional spectra are presented in order to illustrate these points with real examples.