Conundrum in Measured Electron Affinities of Complex Heavy Atoms

Abstract

Low-energy electron scattering from the lanthanide atoms Eu, Tb, Tm, Gd, and Nd including Nb is investigated through calculated electron elastic total cross sections using our robust Regge-pole methodology. The extracted binding energies of the resultant ground and metastable anions formed during the collisions are contrasted with the measured electron affinities (EAs). It is concluded that the measured EAs for these atoms require reinterpretation and new recommended values are presented.

Fullerene Negative Ions: Formation and Catalysis

“…The low-energy electron elastic collision TCSs of the fullerene molecules obtained in this paper as well as those of the already studied fullerenes [18,19,35,36] and the actinide [37] and the lanthanide [38,39] atoms should contribute to a better understanding of the role of the individual atoms/fullerenes in ongoing studies involving endohedral systems [40][41][42][43][44][45][46]. Also expected to benefit from this study will be the exploration of the M@C60 (M = Ti, Zr, U) fullerene hybrids that have demonstrated catalytic efficiency in fundamental hydrogenation [47].…”

Negative Ion Binding Energies in Complex Heavy Systems

“…Most importantly, the ground states anionic BEs are identified with the EAs and compared with the measured and/or calculated values. Indeed, the figures demonstrate the need for delineation and identification of the resonance structures to minimize misidentification of the various sharp peaks as explained in [2]. Suffice to state here that the ground, metastable and excited states anionic BEs of all the complex heavy systems were extracted from such TCSs as in Figures 1 and 2.…”

“…In the lanthanide and actinide atoms, in particular the presence of two or more open d-and f-subshell electrons presents formidable computational complexity when using conventional theoretical methods to calculate electron affinities (EAs) of complex heavy systems. Thus, recent years have witnessed the proliferation in the published literature of incorrect experimental and theoretical EAs for the lanthanide [2] and actinide [3] atoms as well as for atomic Nb. For the complex atoms such as Nb experiments have concentrated efforts mainly on the accuracy rather than on the reliability of the existing EAs.…”

“…(1) In [2] it was concluded that both the measured and the calculated EAs for the lanthanide atoms Eu [4][5][6][7][8], Tb [9,10], Tm [11,12], Gd [5,10] and Nd [5,6,9], including the Nb [13][14][15][16] atom require reinterpretation. New recommended EA values for these atoms were presented.…”

Fullerene Negative Ions: Formation and Catalysis

“…The low-energy electron elastic collision TCSs of the fullerene molecules obtained in this paper as well as those of the already studied fullerenes [18,19,35,36] and the actinide [37] and the lanthanide [38,39] atoms should contribute to a better understanding of the role of the individual atoms/fullerenes in ongoing studies involving endohedral systems [40][41][42][43][44][45][46]. Additionally, expected to benefit from this study will be the exploration of the M@C 60 (M = Ti, Zr,U) fullerene hybrids that have demonstrated catalytic efficiency in fundamental hydrogenation [47].…”