A rigorous probe of the electronic structure of the Bk and Cf actinide atoms through Regge pole-calculated electron elastic cross sections

A recent experiment [1] identified a weak spin-orbit-coupling in Bk while a j-j coupling scheme described Cf. It concluded that these observations strengthen Cf as a transitional element in the actinide series. Regge pole-calculated low-energy electron elastic total cross sections (TCSs) for Bk and Cf atoms are characterized generally by ground, metastable and excited states negative-ion formation, shape resonances (SRs) and Ramsauer-Townsend (R-T) minima [2]. Additionally, a polarization-induced metastable TCS with a deep R-T minimum near threshold is observed in the Bk TCSs, which flips over to a SR appearing very close to threshold in the Cf TCSs [3]. This behavior manifests the size effect and orbital collapse as well as demonstrates the sensitivity of the R-T minima and SRs to the electronic structure of these atoms, thereby permitting their use as novel validation of the experimental observation.

1. 1. A. Müller et al. Nat. Commun 12, 948 (2021).
   
   2. A.Z. Msezane and Z.  Felfli, Atoms 9, 84 (2021).
   
   3. Z. Felfli and A. Z. Msezane, Appl.  Phys. Research,  At Press (2022)