Preface to hard X-ray photo electron spectroscopy (HAXPES)

摘要

Since this special issue of NIMA is devoted to the description of a new direction of research in photoelectron spectroscopy, I believe that it might be of some interest for the reader to get a short account of the earlier development of high-resolution PES. This spectroscopy is based on the photoelectric effect and the existence of well-defined core shell structures of the atomic elements. It is this combination which has made it possible to develop a high-resolution analytical tool to accurately measure the core electron binding energies of all the elements in the periodic system. Such a high-resolution instrument can be called an ESCA instrument (ESCA = Electron Spectroscopy for Chemical Analysis). The binding energies are specific for all atomic elements. In addition to this, electron spectroscopy can also supply detailed information on the valence electron region of molecules and solids (band structures). The external molecular electron orbi-tals in the valence region are directly involved in the chemical bonds between the atomic constituents. These spectra show well-resolved vibrational structures, in some cases even rotational structures when excited by UV or laser radiation.