Inner Shell Photoionization Studies of Atoms and Molecules Using Synchrotron Radiation

Abstract

The continuous nature of synchrotron radiation allows to produce ionization in principle in any subshell of any atom, to explore the energy dependence of photoionization processes over a large energy range and to study special effects following selective excitation of inner electrons at some specific photon energies, like resonance and threshold effects. However, the energy range experimentally accessible with good resolution and intensity is presently limited at about 150 to 200 eV. Below this limit, high photon flux of typically 1012 photons/sec/eV are available and resolution of 50 to 100 meV are currently achievable with good photon flux. Between 200 and 800 eV, the techniques of monochromatization do not yet provide as good experimental conditions as at lower photon energy; the photon flux available is generally sufficient for photoabsorption studies, but the more selective techniques of electron-or ion spectrometries require much higher photon flux. It should be noted also that, above 250 eV, the quasi-photon impact method is still providing higher resolution than synchrotron radiation does.