Laser Resonance Chromatography of Superheavy Elements


Mustapha Laatiaoui, Alexei A. Buchachenko, and Larry A. Viehland

July 13, 2020

Optical spectroscopy constitutes the historical path to accumulate basic knowledge on the atom and its structure. Former work based on fluorescence and resonance ionization spectroscopy enabled identifying optical spectral lines up to element 102, nobelium. The new challenges faced in this research field are the refractory nature of the heavier elements and the decreasing production yields. A new concept of ion-mobility-assisted laser spectroscopy is proposed to overcome the sensitivity limits of atomic structure investigations persisting in the region of the superheavy elements. The concept offers capabilities of both broadband-level searches and high-resolution hyperfine spectroscopy of synthetic elements beyond nobelium.

Exploiting Transport Properties for the Detection of Optical Pumping in Heavy Ions


Mustapha Laatiaoui, Alexei A. Buchachenko, and Larry A. Viehland

July 13, 2020

We present a kinetic model for optical pumping in Lu+ and Lr+ ions as well as a theoretical approach to calculate the transport properties of Lu+ in its ground 1S0 and metastable 3D1 states in helium background gas. Calculations of the initial ion state populations, the field and temperature dependence of the mobilities and diffusion coefficients, and the ion arrival time distributions demonstrate that the ground- and metastable-state ions can be collected and discriminated efficiently under realistic macroscopic conditions.

Mobility of the singly-charged lanthanide and actinide cations: trends and perspectives


Alexei A. Buchachenko, Giorgio Visentin, Larry A. Viehland, and Mustapha Laatiaoui

May 31, 2020

The current status of the 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, 5d 6s or 6s2. The previous theoretical work is extended here to ions of the actinide family with zero electron orbital momentum: Ac+ (7s2, 1S), Am+ (5f7 7s 9S°), Cm+ (5f7 7s2 8S°), No+ (5f14 7s 2S) and Lr+ (5f14 7s2 1S). The calculations reveal large systematic differences in the mobilities of the 7s and 7s2 groups of ions and other similarities with their lanthanide analogs. The correlation of ion-neutral interaction potential 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.

High-precision ab initio calculations of the spectrum of Lr+


E.V. Kahl, J.C. Berengut, M. Laatiaoui, E. Eliav, and A. Borschevsky

December 9, 2019

The planned measurement of optical resonances in singly ionized lawrencium (Z = 103) requires accurate theoretical predictions to narrow the search window. We present high-precision, ab initio calculations of the electronic spectra of Lr+ and its lighter homologue lutetium (Z = 71). We have employed the state-of-theart relativistic Fock space coupled cluster approach as well as the configuration interaction with many-body perturbation theory (CI + MBPT) method to calculate atomic energy levels, g factors, and transition amplitudes and branching ratios. Our calculations are in close agreement with experimentally measured energy levels and transition strengths for the homologue Lu+, and are well converged for Lr+, where we expect a similar level of accuracy. These results present large-scale, systematic calculations of Lr+ and will serve to guide future experimental studies of this ion.