Angular momentum partitioning and hexacontatetrapole moments in impulsively excited argon ions

We have studied polarized electron collisions with Ar in which the target i s simultaneously ionized and excited to form Ar+(3p(4)(D-1)4p) states. We m easured the integrated Stokes parameters of the subsequent fluorescence emi tted by the F-2(7/2), F-2(5/2), D-2(5/2), and P-2(3/2) states along the dir ection of electron polarization. The Rubin-Bederson hypothesis is shown to hold for the L and S multipoles of these states. The electric quadrupole an d hexadecapole of the D-1 core are derived. By recoupling these moments wit h the electric quadrupole moment of the 4p electron, we calculate higher mo ments of the total ionic orbital angular momentum, including its hexacontat etrapole (64-pole) moment.