Abstract
The rigorous Regge pole method has been used to investigate negative-ion formation in the large actinide atoms Cf, Fm and Md through the elastic total cross sections (TCSs) calculation in the electron impact energy range 0.0 ≤ E ≤ 10.0eV. Ground, metastable and excited negative-ion formation as well as shape resonances (SRs) and Ramsauer-Townsend (R-T) minima are found to characterize generally the TCSs which also exhibit fullerene molecular behavior near threshold through the TCSs of the highest excited states, while maintaining atomic character through the ground state TCSs. Additionally, a polarization-induced metastable TCS with a pronounced SR appears for the first time very close to threshold in the Cf TCSs, having flipped over from a deep R-T minimum near threshold in the Bk TCSs. This behavior manifests the impact of the size effect and the 6d-orbital collapse as well as demonstrates the sensitivity of the R-T minima and the SRs to the electronic structure of these atoms, thereby permitting their first ever use as novel confirmation of Cf as a transitional element in the actinide series. Rigorous and unambiguous ground, metastable and excited anionic states BEs extracted from the TCSs are compared with the existing electron affinities.
Highlights
The radioactive actinide atoms, including the At atom are challenging to handle experimentally; making the production of reliable theoretical data essential
The extracted from the total cross sections (TCSs) anion BEs have been compared with the existing theoretical electron affinities (EAs)
We have discovered new manifestations in the low-energy electron scattering TCSs of the Cf, Fm and Md atoms; namely, fullerene molecular behavior near threshold
Summary
The radioactive actinide atoms, including the At atom are challenging to handle experimentally; making the production of reliable theoretical data essential. For the atoms At (Leimbach et al, 2020), Au (Hotop & Lineberger, 2003; Andersen, Haugen, & Hotop, 1999; Zheng et al, 2007) and Pt(Hotop & Lineberger, 2003; Gibson, Davies, & Larson, 1993; Bilodeau, et al, 1999) as well as the fullerene molecules C20 through C92(Msezane & Felfli, 2018a; Felfli & Msezane, 2018a) the measured EAs generally matched excellently the Regge pole-calculated BEs of the ground states of the formed negative ions during the collisions. This gives great credence to our interpretation of the EAs of these heavy multi-electron systems, viz. The Regge pole method requires no assistance whatsoever from either experiment or other theory to achieve the remarkable feat
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