Asymmetric (e,2e) study of the 100-eV ionization of the 3 sigma g and 1 pi u molecular orbitals of N2.

Abstract

Electron-impact ionization of the 3{sigma}{sub {ital g}} and 1{pi}{sub {ital u}} molecular orbitals of N{sub 2} to produce the {ital X}{sup 2}{Sigma}{sup +}{sub {ital g}} and {ital A}{sup 2}{Pi}{sub {ital u}} states of N{sub 2}{sup +} has been investigated in an asymmetric ({ital e},2{ital e}) experiment at the 100-eV maximum of the total ionization cross section. The experiment allows the direct comparison of ionization of two molecular orbitals in the same target molecule. Scattering angles of the incident electron {lt}5{degree} and ejected electron energies from 3 to 13 eV were used. The relative triple differential cross sections were obtained as a function of ejected electron angle for both the binary (parallel to momentum transfer direction) and recoil (antiparallel) directions. The maxima of the binary and recoil peaks were found to be shifted from the angular positions predicted by first-order theory. In contrast to the typical atomic case, the recoil peaks were shifted to smaller ejection angles. In addition, the binary peak of the 1{pi}{sub {ital u}} orbital ionization was located at an angle 30{degree} larger than the corresponding peak for the 3{sigma}{sub {ital g}} orbital. These results suggest that the experiment is very sensitive to the initial and final statesmore » of the target. Differences from results with atomic targets may be related to the nonspherically symmetric nature of the target and residual ion. {copyright} {ital 1996 The American Physical Society.}« less