Tracing Multiple Scattering Patterns in Absolute (e, 2e) Cross Sections for H₂ and He over a 4π Solid Angle

Absolutely normalized (e,2e) measurements for H ₂ and He covering the full solid angle of one ejected electron are presented for 16 eV sum energy of both final state continuum electrons. For both targets rich cross-section structures in addition to the binary and recoil lobes are identified and studied as a function of the fixed electron's emission angle and the energy sharing among both electrons. For H ₂ their behavior is consistent with multiple scattering of the projectile as discussed before. For He the binary and recoil lobes are significantly larger than for H ₂ and partly cover the multiple scattering structures. To highlight these patterns we propose a alternative representation of the triply differential cross section. Nonperturbative calculations are in good agreement with the He results and show discrepancies for H ₂ in the recoil peak region. For H ₂ a perturbative approach reasonably reproduces the cross-section shape but deviates in absolute magnitude.