EVIDENCE OF INITIAL-STATE 2-CENTER EFFECTS FOR (E,2E) REACTIONS

Coincidence, or (e, 2e), measurements of electron-impact ionization of atoms have established that the largest values of triply differential cross sections are obtained in collisions involving small momentum tr ansfer to the target. Absolute measurements for these reactions are no w available for hydrogen at 54.4-eV impact energy, and relative data h ave recently been reported at 27.2 eV. Previous theoretical works have concentrated on employing asymptotically correct two-center wave func tions for the final state, leaving the initial state described by the Born approximation. Here we report results for which asymptotically co rrect two-center wave functions are used for both the initial and fina l states of the scattering system. Comparison of these results with ex periment reveals that two-center effects (projectile-target correlatio ns) are also important in the initial state.