Excitation energies, polarizabilities, multipole transition rates, and lifetimes of ions along the francium isoelectronic sequence

TL;DR

This paper applies advanced relativistic many-body perturbation theory to calculate various atomic properties of ions in the francium isoelectronic sequence, providing benchmark data for energies, transition rates, lifetimes, and polarizabilities.

Contribution

It offers new high-precision calculations of energies, transition rates, lifetimes, and polarizabilities for ions Z=87-100, including all-order methods for improved accuracy.

Findings

Accurate energy levels and transition rates for francium-like ions.

Calculated lifetimes and polarizabilities serving as benchmarks.

Enhanced theoretical understanding of relativistic effects in heavy ions.

Abstract

Relativistic many-body perturbation theory is applied to study properties of ions of the francium isoelectronic sequence. Specifically, energies of the 7s, 7p, 6d, and 5f states of Fr-like ions with nuclear charges Z = 87 - 100 are calculated through third order; reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for 7s - 7p, 7p - 6d, and 6d - 5f electric-dipole transitions; and 7s - 6d, 7s - 5f, and 5f_5/2 - 5f_7/2 multipole matrix elements are evaluated to obtain the lifetimes of low-lying excited states. Moreover, for the ions Z = 87 - 92 calculations are also carried out using the relativistic all-order single-double method, in which single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. With the aid of the SD wave functions, we obtain accurate values of energies, transition rates, oscillator strengths, and the lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra II, Ac III, and Th IV are calculated using relativistic third-order and all-order methods. Ground state scalar polarizabilities for other Fr-like ions are calculated using a relativistic second-order method. These calculations provide a theoretical benchmark for comparison with experiment and theory.