Collisionally induced alignment produced by electron and light-ion impact: Auger electron emission following 2p ionisation and excitation

Abstract

A detailed study of the collisionally induced alignment of the 2p electron is presented. The collision systems investigated are e-, H+, He and Li+ with Mg for emission following 2p ionisation and e- and H+ with Na and Mg+ with He for emission following 2 p excitation. Impact velocities, scaled with respect to the threshold velocity of the process being studied, ranged from approximately electron threshold ( nu rel=1) to nu rel=7 for electron impact and nu rel=0.1-5 for the combined ion impact data. A comparison of the measured alignments for the various projectiles with each other and with theory is made for the two cases. Specific comparisons demonstrate how kinematics effect at lower velocities. In addition, pronounced maxima-minima structures resulting from nodes in the target wavefunctions are observed. Finally, the fires measurements of alignment in the region of electron threshold are presented and a prediction of the threshold alignment value is made in the case of 2p ionisation by electron impact.