Fully differential cross sections for Li²⁺-impact ionization of Li(2s) and Li(2p)

Abstract

A semiclassical impact parameter version of the continuum distorted wave-Eikonal initial state theory is developed to study the differential ionization of Li atoms in collisions with Li 2+ ions. Both post and prior forms of the transition amplitude are considered. The fully differential cross sections are calculated for the lithium targets in their ground and their first excited states and for the projectile ions at 16 MeV impact energy. The role of the internuclear interaction as well as the significance of the post-prior discrepancy in the ejected electron spectra are investigated. The obtained results for ejection of the electron into the azimuthal plane are compared with the recent measurements and with their corresponding values obtained using a fully quantum mechanical version of the theory. In most of the cases, the consistency of the present approach with the experimental and the quantum theoretical data is reasonable. However, for 2p-state ionization, in the cases where no experimental data exist, there is a considerable difference between the two theoretical approaches. This difference is questionable and further experiments are needed to judge which theory makes a more accurate description of the collision dynamics.

Fully differential cross sections for ionization of Li(2s) and Li(2p) by 16 MeV Li2+ impact

“…Measurements for the FDCS were also reported for the 24 MeV O 8+ and 16 MeV Li 2+ impacts [12][13][14][15]. The results of these experiments were analyzed in [8,9,[12][13][14][15][16][17]. The experimental and theoretical results for the DDCSs and FDCSs are found to be in good qualitative agreement.…”

“…The measured FDCSs [15] were reported for electrons ejected into the azimuthal plane with energy ε e =2, 10 and 20 eV and for q=0.4 and 1.0 projectile momentum transfer values. The measured data were analyzed using the 3DW-EIS [15] and continuum distorted wave with eikonal initial sate (CDW-EIS) [17] approximation. Results of the two calculations are overall in good agreement, but discrepancies are observable for some combinations of q and ε e .…”

“…Results of the two calculations are overall in good agreement, but discrepancies are observable for some combinations of q and ε e . The need for further experiments was stressed in [17] to have a more accurate tests for effectiveness of the theories. In the calculations of [15,17], the interactions of the Li + (1s 2 ) core with the ionized electron and with projectile are approximated by their asymptotic Coulomb potentials.…”

“…The need for further experiments was stressed in [17] to have a more accurate tests for effectiveness of the theories. In the calculations of [15,17], the interactions of the Li + (1s 2 ) core with the ionized electron and with projectile are approximated by their asymptotic Coulomb potentials. These interactions are treated more realistically in the present CDW-EIS calculation.…”

“…For the Li(2p) target, the FDCS is asymmetric with respect to the scattering plane due to the unequal m-sublevel population (m=−1, 0, 1) of the target, which is called magnetic or orientational dichroism [12,18,19]. Furthermore, a double-peak structure in the angular distribution was discussed in [15,17]. This structure was attributed to the angular part of the initial bound state orbital of the active electron and to kinematical conditions.…”