High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the ${\mathrm{Xe}}^{+}$ data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms.

• Received 13 May 1986

DOI:https://doi.org/10.1103/PhysRevA.35.1033