Chemical shifts in X-ray and photo-electron spectroscopy: a historical review

A review with historical emphasis is given of the discovery and evaluation of chemical shifts in X-ray and photo-electron spectroscopy. The discovery and interpretation of the shifts in the X-ray spectra in the early 1920s are treated as an introduction and general background. The discovery of the shifts in photo-electron spectra, discovered in the late 1950s, and its interpretation, which led to the invention of the electron spectroscopy for chemical analysis (ESCA) method in the early 1960s, are then reviewed. Various methods of evaluating the core-electron binding energies and chemical shift are discussed-from atomic self-consistent field calculations in the early 1960s to quite sophisticated many-body and density-functional calculation in the late 1990s. (C) 2004 Published by Elsevier B.V.