Low-Energy Electron Elastic Total Cross Sections for Ho, Er, Tm, Yb, Lu, and Hf Atoms

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.

Low-Energy Electron Elastic Collisions with Actinide Atoms Am, Cm, Bk, Es, No and Lr: Negative-Ion Formation

“…Additionally, recently the EAs of Th and Hf were measured [5,6]. For both atoms the measured and calculated EAs corresponded to the Regge-pole-calculated BEs of their anions in excited states [7,8] and not in their ground states.…”

“…These two important effects are identified as the major physical effects mostly responsible for electron attachment in low-energy electron scattering from complex heavy systems, leading to stable negative-ion formation. These effects are particularly important in the study of the experimentally difficult-to-handle radioactive actinide atoms, and because of the difficulty experienced by conventional theoretical calculations to obtain unambiguous and reliable EAs for the lanthanide and actinide atoms [7][8][9]35]. Crucial in the CAM methods are the Regge trajectories, viz.…”

“…Clearly, the analysis leaves one much confused regarding the meaning of the EAs of the actinide atoms as was the case with the lanthanide atoms [8]. Indeed, the sophisticated theoretical methods experience difficulties producing unambiguous and reliable EAs of the actinide atoms.…”

“…This renders obtaining unambiguous and reliable EAs for these systems very difficult, if not impossible. Indeed, many existing experimental and sophisticated theoretical EAs of the lanthanides and actinides are difficult to interpret, see for example [7][8][9][10]. A serious question then arises: Does the EA of complex heavy systems correspond to the BE of electron attachment in the ground, metastable or the excited state of the formed negative ion during the collision?…”

Doubly-Charged Negative Ions as Novel Tunable Catalysts: Graphene and Fullerene Molecules Versus Atomic Metals

“…Very recently, the EAs of At was measured [21], as well as that of atomic Th [38]. However, the latter EA value has been identified with the BE of an excited state of Th [39]. Figure 3 compares the Regge-pole calculated TCSs for the large actinide atoms Cm and No.…”