Photoionization of open-shell atoms: oxygen and the halogens

Photoionization of open-shell atoms at the level of detailed electron dynamics, as determined from electron spectrometry analysis, has remained relatively unexplored until recent years because of the difficulty of generating a suitable source of the free radical species, particularly for the elements that are gaseous dimers under normal conditions. However, the development of a microwave-discharge-powered apparatus that could serve as the source for an electron spectrometer made it possible to undertake an extensive study of the photoionization dynamics of four of these elements, atomic oxygen, fluorine, chlorine, and bromine, as observed primarily in the electron ionization channel. This report presents a brief review of the results that have been obtained for measurements on these species, with an emphasis on the principal physics characterizing the behavior as opposed to the specific spectroscopic details. These latter are covered in the many reports that are referenced. (C) 2003 Elsevier Ltd. All rights reserved.