Alignment of 2P3/2 vacancy state in uranium produced after photoionization

The alignment of 2P3/2 vacancy state in uranium produced purely by photoionization and unaltered by C-K transfer has been investigated. The experiment has been performed by measuring the differential L1, Lα and Lβ x-ray production cross sections in uranium by Mo K x-rays at angles 30 and 90 degrees. It is seen that K x-ray energy of Mo is above L3 subshell but below L2 subshell edge energies of uranium and thus K, L1 and L2 sub shells of uranium are not ionised. Mo K x-rays produced as a result of interaction of 59.57 keV gamma rays emitted from a 1 Curie241Am source were collimated to fall on a thick uranium target. The uranium L x-rays emitted as a result of the interaction of Mo K x-rays with L3 subshell electrons of uranium at angles 30 and 90 degree with respect to the incident beam were recorded with a Si(Li) x-ray detector with resolution of the order of 180 eV at Mn K x-ray energy. The results of the present experiment show that all the three groups i.e. L1, Lα and Lβ are emitted anisotropically while in the earlier cases, where Coster-Kronig transitions are active, Lβ group was found to be relatively isotropic. This confirm the view that the photon induced vacancies in 2P3/2 state are aligned and those in 2S1/2 and 2P1/2 states are unaligned. (author). 8 refs., 1 tab