Correlation diagrams: their use in the interpretation of heavy ion-atom inelastic collisions

The orbital energy against internuclear separation curves 'correlation diagrams' for the symmetric Ne-Ne and the asymmetric Ne-Ar systems have been determined using an ab initio Hartree-Fock molecular orbital method. On the basis of these findings the usefulness of the electron- promotion mechanism, proposed by Fano and Lichten (1965) in accounting for inner-shell vacancy formation resulting from heavy ion-atom collisions is evaluated. The mechanism is considered to be of most value in explaining the findings related to the formation of L shell vacancies. In some asymmetric systems where there is evidence for the production of K shell vacancies it has been shown that the electron-promotion mechanism is not applicable. Other experimental results are interpreted as providing direct evidence that the adiabatic approximation is not strictly valid for these collision processes. The findings suggest that more detailed calculations using a modification of direct scattering theory are required.