Abstract
The robust Regge-pole methodology wherein is fully embedded the essential electron-electron correlation effects and the vital core polarization interaction has been used to explore negative ion formation in the large lanthanide Ho, Er, Tm, Yb, Lu, and Hf atoms through the electron elastic total cross sections (TCSs) calculations. These TCSs are characterized generally by dramatically sharp resonances manifesting ground, metastable, and excited negative ion formation during the collisions, Ramsauer-Townsend minima, and shape resonances. The novelty and generality of the Regge-pole approach is in the extraction of the negative ion binding energies (BEs) of complex heavy systems from the calculated electron TCSs. The extracted anionic BEs from the ground state TCSs for Ho, Er, Tm, Yb, Lu, and Hf atoms are 3.51 eV, 3.53 eV, 3.36 eV, 3.49 eV, 4.09 eV and 1.68 eV, respectively. The TCSs are presented and the extracted from the ground; metastable and excited anionic states BEs are compared with the available measured and/or calculated electron affinities. We conclude with a remark on the existing inconsistencies in the meaning of the electron affinity among the various measurements and/or calculations in the investigated atoms and make a recommendation to resolve the ambiguity.
Highlights
There is a great need to understand and clarify the measured and/or calculated electron affinities (EAs) of the large lanthanide and Hf atoms
In the Au, Pt, and At atoms as well as the C60 and other fullerene molecules, the meaning of the EAs was in the context of electron attachment to the ground state of neutral complex heavy systems
In this paper, the EAs of the lanthanide and Hf atoms are determined and discussed in this context, namely electron attachment to the ground state of the neutral atoms resulting in stable negative ion formation
Summary
There is a great need to understand and clarify the measured and/or calculated electron affinities (EAs) of the large lanthanide and Hf atoms. Single atoms play an essential role in catalysis through negative ion formation in low-energy electron elastic collisions. Calculated low-energy electron elastic TCSs for complex heavy systems, including fullerene molecules, are characterized generally by ground, metastable and excited negative ion formation, shape resonances, and Ramsauer-Townsend (R-T) minima. The presence of metastable and excited anions in the TCSs for the lanthanide and actinide atoms impacts significantly the reliability of both the measured and the calculated EAs in addition to leading to ambiguous EAs. The fundamental mechanism underlying atomic negative-ion catalysis and requiring reliable EAs was proposed by our group in the context of muon catalyzed nuclear fusion involving a negative muon, a deuteron, and a triton [2,3]. The negative ion catalysis mechanism requires the delineation and identification of the ground, metastable, and excited states anionic binding energies (BEs) of the formed negative ions during the collision of
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