Multiple Ionization of Ne, Ar, and Kr Produced by X Rays in the Energy Range 0.28-8.03 keV

Relative abundances of multiply charged neon, argon, and krypton ions produced by x rays of energies 0.28, 1.5, 5.4, and 8.0 keV have been measured with a time-of-flight mass spectrometer. Effectively monoenergetic x rays were obtained by a filtering technique whereby two filters with transmissions matching at all energies except at the $K$ characteristic line of the x-ray tube target material were alternately placed in the x-ray beam. The data when corrected for charge-dependent discrimination effects are consistent with previous measurements and, except for neon, with calculations which include the electron shakeoff mechanism in addition to Auger transitions. The results for neon at 0.28 keV confirm the need for including electron correlation effects in the description of the ionization process. Other discrepancies between theory and experiment can be explained by considering the energy dependence of partial photoionization cross sections calculated by Rakavy and Ron.