Mobility of the Singly-Charged Lanthanide and Actinide Cations: Trends and Perspectives

TL;DR

This review discusses the current understanding of the mobility of singly-charged lanthanide and actinide ions in gases, highlighting their electronic configuration dependence, theoretical modeling, and implications for superheavy ion research.

Contribution

The paper extends theoretical calculations of ion mobility to actinide ions with zero orbital momentum, revealing systematic differences and similarities with lanthanide ions, and discusses their potential for superheavy ion applications.

Findings

Mobility is highly sensitive to electronic configuration.

Theoretical models show systematic differences between 7s and 7s$^2$ ions.

Qualitative trends support superheavy ion research, but experimental data are limited.

Abstract

The current status of gaseous transport studies of the singly-charged lanthanide and actinide ions is reviewed in light of potential applications to superheavy ions. The measurements and calculations for the mobility of lanthanide ions in He and Ar agree well, and they are remarkably sensitive to the electronic configuration of the ion, namely, whether the outer electronic shells are 6s, 5d6s or 6s$^2$. The previous theoretical work is extended here to ions of the actinide family with zero electron orbital momentum: Ac$^+$ (7s$^2$, $^1$S), Am$^+$ (5f$^7$7s $^9$S$^\circ$), Cm$^+$ (5f$^7$7s$^2$ $^8$S$^\circ$), No$^+$ (5f$^{14}$7s $^2$S) and Lr$^+$ (5f$^{14}$7s$^2$ $^1$S). The calculations reveal large systematic differences in the mobilities of the 7s and 7s$^2$ groups of ions and other similarities with their lanthanide analogs. The correlation of ion-neutral interaction potentials and mobility variations with spatial parameters of the electron distributions in the bare ions is explored through the ionic radii concept. While the qualitative trends found for interaction potentials and mobilities render them appealing for superheavy ion research, lack of experimental data and limitations of the scalar relativistic ab initio approaches in use make further efforts necessary to bring the transport measurements into the inventory of techniques operating in ''one atom at a time'' mode.