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Abstract

Auger electrons emitted at fixed kinetic energy in multiple-ionization processes are not only characteristic for inner-shell transitions but also for valence double photoionization. The status of the spectroscopy of these valence Auger electrons which are emitted at low kinetic energies is reviewed including data from atomic and molecular photoionization. Besides the well-known show cases for valence Auger spectroscopy in atoms and molecules, neon and carbon monoxide, new results are presented for heavier rare gases and N₂. The relation between these Auger lines and the presence of Auger lines at very low kinetic energy in resonant and regular inner-shell Auger spectra is emphasized. Partial cross sections and angular distributions are discussed with respect to a deeper understanding of the occurrence of satellite lines in photoelectron spectra and their description in terms of transition matrix elements.