Coplanar symmetric (e, 2e) cross sections for krypton 4s ionization

Abstract

The triple-differential cross section for electron impact ionization of the 4sorbital of krypton (binding energy 27.5 eV) has been measured in coplanarsymmetric kinematics. The experimental results are presented for outgoingelectron energies of 85, 50, 20, 10 and 4 eV. The results are comparedwith two distorted wave Born approximation calculations; the influenceof post-collision interaction (PCI) on the cross sections is investigatedby incorporating correct final state boundary conditions in one of thecalculations. The influence of PCI is found to be very important at thelower energies. Inclusion of the three-body final state boundary conditionsimproves the agreement between theory and experiment, but there are stillsignificant discrepancies, indicating that additional physical effects (suchas higher-order interactions) are important at lower energies.