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

Atoms ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 17
Author(s):  
Zineb Felfli ◽  
Alfred Z. Msezane
Keyword(s):  
Cross Sections ◽  
Regge Pole ◽  
Binding Energies ◽  
Negative Ion ◽  
Ion Binding ◽  
Electron Affinities ◽  
Total Cross Sections ◽  
Ion Formation ◽  
Electron Correlation Effects ◽  
Low Energy Electron

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.

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

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 84
Author(s):  
Alfred Z. Msezane ◽  
Zineb Felfli
Keyword(s):  
Cross Sections ◽  
Regge Pole ◽  
Binding Energies ◽  
Negative Ion ◽  
Shape Resonance ◽  
Ion Binding ◽  
Total Cross Sections ◽  
Ion Formation ◽  
Molecular Behavior ◽  
Low Energy Electron

The rigorous Regge-pole method is used to investigate negative-ion formation in actinide atoms through electron elastic total cross sections (TCSs) calculation. The TCSs are found to be characterized generally by negative-ion formations, shape resonances and Ramsauer-Townsend(R-T) minima, and they exhibit both atomic and fullerene molecular behavior near the threshold. Additionally, a polarization-induced metastable cross section with a deep R-T minimum is identified near the threshold in the Am, Cm and Bk TCSs, which flips over to a shape resonance appearing very close to the threshold in the TCSs for Es, No and Lr. We attribute these new manifestations to size effects and orbital collapse significantly impacting the polarization interaction. From the TCSs unambiguous and reliable ground, metastable and excited states negative-ion binding energies (BEs) for Am−, Cm−, Bk−, Es−, No− and Lr− anions formed during the collisions are extracted and compared with existing electron affinities (EAs) of the atoms. The novelty of the Regge-pole approach is in the extraction of the negative-ion BEs from the TCSs. We conclude that the existing theoretical EAs of the actinide atoms and the recently measured EA of Th correspond to excited anionic BEs.

scholarly journals Negative Ion Formation in Low-Energy Electron Collisions with the Actinide Atoms Th, Pa, U, Np and Pu

2019 ◽  
Vol 11 (1) ◽  
pp. 52 ◽  
Author(s):  
Zineb Felfli ◽  
Alfred Z. Msezane
Keyword(s):  
Theoretical Calculations ◽  
Regge Pole ◽  
Binding Energies ◽  
Low Energy ◽  
Energy Electron ◽  
Negative Ion ◽  
Electron Affinities ◽  
Electron Collisions ◽  
Ion Formation ◽  
Low Energy Electron

Here we investigate ground and metastable negative ion formation in low-energy electron collisions with the actinide atoms Th, Pa, U, Np and Pu through the elastic total cross sections (TCSs) calculations. For these atoms, the presence of two or more open d- and f- subshell electrons presents a formidable computational task for conventional theoretical methods, making it difficult to interpret the calculated results. Our robust Regge pole methodology which embeds the crucial electron correlations and the vital core-polarization interaction is used for the calculations. These are the major physical effects mostly responsible for stable negative ion formation in low-energy electron scattering from complex heavy systems. We find that the TCSs are characterized generally by Ramsauer-Townsend minima, shape resonances and dramatically sharp resonances manifesting ground and metastable negative ion formation during the collisions. The extracted from the ground states TCSs anionic binding energies (BEs) are found to be 3.09eV, 2.98eV, 3.03eV, 3.06eV and 3.25eV for Th, Pa, U, Np and Pu, respectively. Interestingly, an additional polarization-induced metastable TCS with anionic BE value of 1.22eV is generated in Pu due to the size effect. We also found that our excited states anionic BEs for several of these atoms compare well with the existing theoretical electron affinities including those calculated using the relativistic configuration-interaction method. We conclude that the existing theoretical calculations tend to identify incorrectly the BEs of the resultant excited anionic states with the electron affinities of the investigated actinide atoms; this demonstrates the great need for experimental verification and unambiguous determination of their electron affinities.

scholarly journals Fullerene Negative Ions: Formation and Catalysis

2020 ◽  
Author(s):  
Zineb Felfli ◽  
Kelvin Suggs ◽  
Nantambu Nicholas ◽  
Alfred Z. Msezane
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Water Oxidation ◽  
Regge Pole ◽  
Negative Ions ◽  
Negative Ion ◽  
Total Cross Sections ◽  
Hydrogen Bond Strength ◽  
Low Energy Electron ◽  
Fundamental Mechanism

We first explore negative-ion formation in fullerenes C44, C60, C70, C98, C112, C120, C132 and C136 through low-energy electron elastic scattering total cross sections calculations using our Regge-pole methodology. Water oxidation to peroxide and water synthesis from H2 and O2 are then investigated using the anionic catalysts C44ˉ to C136ˉ. The fundamental mechanism underlying negative-ion catalysis involves hydrogen bond strength-weakening in the transition state. DFT transition state calculations found C60ˉ numerically stable for both water and peroxide synthesis, C100ˉ increases the energy barrier the most and C136ˉ the most effective catalyst in both water synthesis and oxidation to H2O2.

scholarly journals Fullerene Negative Ions: Formation and Catalysis

2020 ◽  
Vol 21 (9) ◽  
pp. 3159
Author(s):  
Zineb Felfli ◽  
Kelvin Suggs ◽  
Nantambu Nicholas ◽  
Alfred Z. Msezane
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Water Oxidation ◽  
Density Functional ◽  
Regge Pole ◽  
Negative Ions ◽  
State Density ◽  
Negative Ion ◽  
Functional Theory ◽  
Total Cross Sections

We first explore negative-ion formation in fullerenes C44 to C136 through low-energy electron elastic scattering total cross sections calculations using our Regge-pole methodology. Then, the formed negative ions C44ˉ to C136ˉ are used to investigate the catalysis of water oxidation to peroxide and water synthesis from H2 and O2. The exploited fundamental mechanism underlying negative-ion catalysis involves hydrogen bond strength-weakening/breaking in the transition state. Density Functional Theory transition state calculations found C60ˉ optimal for both water and peroxide synthesis, C100ˉ increases the energy barrier the most, and C136ˉ the most effective catalyst in both water synthesis and oxidation to H2O2.

Low-energy electron elastic scattering from complex atoms: Nd, Eu, and Tm

2009 ◽  
Vol 87 (4) ◽  
pp. 321-327 ◽  
Author(s):  
Z. Felfli ◽  
A. Z. Msezane ◽  
D. Sokolovski
Keyword(s):  
Cross Sections ◽  
Regge Pole ◽  
Electron Attachment ◽  
Negative Ions ◽  
Binding Energies ◽  
Low Energy ◽  
Low Energy Electron ◽  
Experimental Values ◽  
First Time ◽  
Type Potential

The recent Regge-pole methodology, which includes the essential electron correlations, is employed together with a Thomas–Fermi type potential incorporating the vital core-polarization interaction to calculate low-energy (E less than or equal to 1 eV) electron elastic total and Mulholland cross sections for the complex atoms Nd, Eu, and Tm, found to be characterized by subtle Regge resonances, for a fundamental understanding of the mechanism of the near-threshold electron attachment. The binding energies of the complex negative ions Nd–, Eu–, and Tm– formed through the collisions as Regge resonances are extracted for the first time from the resonances and compared with the latest theoretical and experimental values. Ramsauer–Townsend minima, shape resonances, and the Wigner threshold behavior are also obtained.

Partial cross sections for positive and negative ion formation following electron impact on uracil

2004 ◽  
Vol 37 (15) ◽  
pp. 3013-3020 ◽  
Author(s):  
S Feil ◽  
K Gluch ◽  
S Matt-Leubner ◽  
P Scheier ◽  
J Limtrakul ◽  
...  
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Negative Ion ◽  
Ion Formation
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