AUGER-ELECTRON PHOTOION COINCIDENCE MEASUREMENTS OF ATOMS AND MOLECULES USING X-RAY SYNCHROTRON-RADIATION

As the availability of intense beams of hard X-rays from synchrotron-r adiation sources has increased, interest in the fundamental interactio ns of X-rays with deep core electrons in free atoms and molecules has undergone a resurgence. These powerful X-ray sources have led to more highly differential measurements, providing ever more detailed informa tion about atomic and molecular structure and dynamics. One such impro vement in measurement technique is the application of electron-ion coi ncidence spectroscopy, which only recently has been extended to studie s of deep core levels. A collaborative research program focusing on th e dynamics of photoionization and Auger decay following hard X-ray abs orption by atoms and small molecules, as well as subsequent fragmentat ion in the molecular case, has been ongoing at the National Synchrotro n Light Source for the past few years. This report summarizes the capa bilities of the program by reviewing results on argon near the K edge, and discusses briefly newer measurements on xenon and a few sulfur- a nd chlorine-containing molecules.