ENERGY-DEPENDENCE OF L3-SHELL ALIGNMENT OF ARGON FOLLOWING ELECTRON-IMPACT IONIZATION

The L3-shell alignment of argon has been investigated by measuring the angular distribution of L3-M2,3M 2,3 (1S0) Auger electrons, for incident electron energies between 350 eV and 50 keV (the binding energy E B(L3) is 248.5 eV). The results are discussed separately for different energy regions. It has been shown that threshold alignment is not determined by simple angular momentum arguments, as in the case of impact excitation. In the region of first Born approximation, comparison with existing calculations using screened hydrogenic and Hartree-Slater wavefunctions exhibited good agreement. The influence of the use of the correct binding energy Ebexp in the screened hydrogenic model is discussed. Calculated alignment curves are presented for different parameters theta L=Ebuexp(l3)/EB scrhyd for incident energies up to T-320 EB.