Forward-backward asymmetry in the inelastic scattering of electrons from highly charged ions

Energy-dependent, absolute differential cross sections for 1s --> 2l excita tion in F8+ by the scattering of quasi-free target electrons have been meas ured. The formation and subsequent decay of the F7+ (3lnl') (n greater than or equal to 3) doubly excited intermediate states gives rise to a resonant inelastic scattering amplitude which is coherent with the nonresonant inel astic scattering. A strong forward-backward asymmetry was found for the ine lastically scattered electrons due to the interference between these two sc attering amplitudes. Close-coupling R-matrix calculations show excellent ag reement with the experiment and thereby demonstrates a method for obtaining high-resolution, angle-resolved differential inelastic electron-ion scatte ring cross sections.