L X-ray anisotropy and L3-subshell alignment of heavy atoms induced by ion impact

Abstract

The anisotropy emission of the Ll X-ray line from heavy atoms (54<or=Z2<or=92) has been investigated experimentally for ion impact (1<or=Z1<or=79) in the energy range 0.15 to 10 MeV amu-1. In the case of single ionisation, the collisionally induced alignment of the L3subshell can be derived. The data for H and He projectiles are reasonably well described by direct Coulomb ionisation theories. With increasing Z1, the measured anisotropy becomes considerably smaller than for H impact. No pronounced dependence on the projectile nuclear charge is found although for different projectiles different ionisation mechanisms (direct ionisation, promotion of molecular orbitals) dominate.