Alfred Msezane Physical Sciences︱ energy released when one electron is added to a neutral atom to form a negative ion. The determination of reliable values of electron affinities for complex heavy systems like Designua/Shutterstock.com lanthanides, actinides, and fullerene A rigorous model of molecules is currently one of the most challenging problems in atomic and molecular physics, both experimentally and theoretically. electron attachment Theoretical models of electron affinity determination must consider that a large number of electrons within the atom are interacting among in lanthanide atoms themselves, and with the incoming low-energy electron. This gives rise to Understanding the physical anthanides, along with the large negatively charged ions, or two important quantum-mechanical mechanism underlying actinide atoms, are a group of anions. The prospect of understanding phenomena – the electron-electron negative ion formation in Latoms that occupy large blocks and controlling the formation of these correlation and the core polarisation low-energy electron collisions near the bottom of the Periodic anionic species is of extraordinary interaction – which play a crucial with lanthanide atoms is of Table. They are heavy and complex interest from a fundamental physical role in the electron attachment fundamental importance in atoms, containing between 57 and perspective, but it can also give process. Although sophisticated physics and chemistry. It also 71 electrons orbiting in complex access to unprecedented and exotic computational approaches, such as has important implications for trajectories around a positive nucleus, chemical processes, which have great the relativistic configuration interaction The ability of an atom to bind an excess electron is called the electron affinity of the atom. a wide range of applications, with velocities of about 1% the speed technological and societal impact. method, can be used to estimate from catalysis to drug delivery of light. Lanthanides play important For instance, heavy negative ions electron affinities, their use is often and water purification. roles in modern chemistry and exhibit can provide efficient and inexpensive cumbersome, demanding and plagued Unfortunately, the complexity a number of unique properties, making catalysts for water purification in by uncertainty, because of the large Msezane has formulated a novel of the interactions among them suitable for applications in chemical reactions that involve the number of electron configurations electrons in lanthanides has for catalysis, superconducting devices, conversion of water into hydrogen which must be included in the mathematical approach – called the a long time made it virtually optoelectronics and fluorescent peroxide. This can potentially be calculations in the case of lanthanides. impossible to reliably predict materials for drug discovery. They are applied to the large-scale processing Also, the interpretation of the Regge pole method – for low-energy the energetics of the electron also used to regulate nuclear reactors. of water for civil uses in developing calculated results can be plagued by binding and the properties of countries. ambiguities. electron collision with heavy many- the resulting negative ions. Most of the chemical applications of Professor Alfred Msezane electron systems. lanthanides exploit their positively Professor Msezane’s research is devoted and his group at Clark Atlanta THE ELECTRON University have developed charged ions (lanthanide atoms with to developing rigorous and accurate ATTACHMENT MECHANISM The Regge pole method, developed by the Regge pole method is its unique a rigorous and powerful two or three electrons removed, for theoretical frameworks to account for As a low-energy electron (incident) Msezane, is capable of accounting for ability to identify the essential states theoretical description of the instance). More recently, however, the physical phenomena occurring approaches a neutral lanthanide the essential physical effects in their full of the anion that can form during electron attachment process in increasing attention has been devoted when lanthanide atoms (and related atom, it initially travels along a linear complexity and provides quantitative the collision, and to determine lanthanide atoms. to the ability of lanthanide atoms to systems, such as actinide atoms and path, similar to a bullet approaching estimates of electron affinities. Crucially, unambiguously the binding energy interact with beams of low-energy fullerene molecules) interact with low- its target. However, in the vicinity of Msezane’s approach does not require of its ground state, from which the electrons, bind with them, and form energy electrons. He has formulated a the atom, the complex interaction input from either experiments or other electron affinity can be extracted. novel mathematical approach – called between the incident electron and theory; it can therefore be used to the Regge pole method – for the the electrons belonging to the atom study electron attachment in systems SCATTERING TOTAL prediction of electron attachment to causes the electron to deviate (or for which measured values are not CROSS SECTIONS heavy many-electron systems, yielding ‘scatter’) from its original path. The available, and to aid the interpretation The central quantity determining the stable negative ions. The method magnitude of this deviation is linked of experimental data. effectiveness of scattering interactions is proving to be a major theoretical to a quantum-mechanical property during anion formation in low-energy breakthrough in unveiling the complex of the incident electron (its complex It is important to realise that the electron scattering experiments is quantum-mechanical interactions at angular momentum) and to its velocity, incident electron may not always the elastic total cross section. It can play during the formation of lanthanide which is related to its kinetic energy. In occupy the ground state of the be interpreted as a cross sectional anions. some cases, the effect of the scattering newly formed anion. Metastable and area in the vicinity of the neutral atom can be sufficient for the electron to excited states can in fact also play within which quantum-mechanical ELECTRON AFFINITY become trapped. In this situation, the a role in the anion formation, and interactions cause the incoming The central physical measure for the electron effectively occupies a new they can substantially complicate electron to experience scattering. ability of an atom to bind an excess stable quantum-mechanical state within the interpretation of experimental The second important quantity is the electron is called the electron affinity the atom, and the system acquires a measurements and theoretical electron binding energy, which is the yaruna/Shutterstock.com of the atom. This can be defined as the negative charge. calculations. One of the strengths of minimum energy required to form a www.researchoutreach.org www.researchoutreach.org of the ambiguities that make these data difficult to interpret. “Many existing experimental measurements Behind the Research and sophisticated theoretical calculations”, says Msezane, “have considered the anionic binding Professor Alfred Msezane Leonid Andronov/Shutterstock.com Leonid Igor Petrushenko/Shutterstock.comIgor energies of the stable, metastable and/or excited negative ion formation E: [email protected] T: +1 404 880 8663 W: https://www.cau.edu/ to correspond to the electron affinities of the considered lanthanide and actinide atoms. This is contrary to the Research Objectives References usual meaning of the electron affinities found in standard measurements of Professor Alfred Msezane has developed a new robust Felfli, Z Msezane, AZ (2018). Conundrum in Measured complex systems, such as Au, Pt, At method for calculating the electron attachment process Electron Affinities of Complex Heavy Atoms.Journal of and fullerene molecules.” Indeed, in lanthanide atoms. Atomic, Molecular, Condensate & Nano Physics, 5(2), 1–8. there are cases in which conventional http://dx.doi.org/10.26713%2Fjamcnp.v5i2.1093 theoretical methods or experimental Detail BlueRingMedia/Shutterstock.com measurements fail to provide a correct Felfli, Z Msezane, AZ (2019). Low-energy electron interpretation of the electron affinities, Address scattering from atomic Th, Pa, U, Np and Pu: Negative White Space Illustrations/Shutterstock.com Space White and they can yield binding energies Department of Physics & CTSPS, Clark Atlanta University ion formation. Applied Physics Research, 11, 52. DOI: that correspond to those of quantum- 223 James P. Brawley Drive SW 10.5539/apr.v11n1p52 mechanical states of the anion which Atlanta, Georgia 30314, USA are not the ground state. Felfli, Z Msezane, AZ (2020). Low-Energy Electron Elastic Bio Total Cross Sections for Ho, Er, Tm, Yb, Lu, and Hf Atoms. Fullerenes (C60 and C70), and the Au and Pt atoms. Professor Msezane and his collaborator Alfred Msezane, Professor of Physics and Founding Atoms, 8, 17. https://doi.org/10.3390/atoms8020017 Dr Zineb Felfli have demonstrated this Director of CTSPS at Clark Atlanta University, is a to be the case in an elegant study of Fellow of Royal Society of Chemistry, American Physical Msezane, AZ (2021). Alfred Msezane. [online] Wikipedia. the theoretically and experimentally Society, Institute of Physics and AAAS. He holds B.Sc Available at: https://en.wikipedia.org/wiki/Alfred_Msezane It provides a robust and reliable method determined