Negative-ion resonances in cross sections for slow-electron–heavy-alkali-metal-atom scattering

We analyze negative-ion resonances in elastic and inelastic total scattering cross sections for slow electron collisions with the heavy-alkali-metal atoms Rb, Cs, and Fr. Our calculations are based on the Dirac R-matrix method [Thumm and Norcross, Phys. Rev. A 45, 6349 (1992)]. For incident electrons of up to 2.8 eV kinetic energy, we compare a ³Pᵒ shape resonance and ³Pᵉ, ¹P₁ᵒ, and ¹D₂ᵒ Feshbach resonances, located below the first excitation threshold of the atomic target in the low-lying spectra of the Rb^-, Cs^-, and Fr^- negative ions, with available experimental data and other calculations. We provide the resonance parameters, partial and converged total elastic and inelastic scattering cross sections, and discuss the relative importance of relativistic effects for the three heavy-alkali-metal targets.