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 ${\mathrm{Rb}}^{\ensuremath{-}},$ ${\mathrm{Cs}}^{\ensuremath{-}},$ and ${\mathrm{Fr}}^{\ensuremath{-}}$ 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.
Simple ionic systems were studied, such as metastable autoionizing states of the negative He ion, two-photon decay spectrum of metastable He ion, optical excitation with low energy ions, and lifetime measurements of singly ionized Li and metastable He ion. Simple atomic systems were also investigated. Metastable autoionizing atomic energy levels in alkali elements were included, along with lifetime measurements of Cr-53, group 2A isotopes, and alkali metal atoms using level crossing and optical double resonance spectroscopy.
The aim of this thesis is to extend the study of multiphoton processes to the heavier negative ions of the alkali-metal atoms and thus, Na"- and K"- were natural candidates for this investigation. The main idea is to achieve an homogeneous description of negative alkaline ions and their response to an intense laser field. This idea has been suggested by recent experimental findings for negative alkaline ions which have revealed a rich structure of their scattering and photodetachment spectra, showing the existence of high-lying temporary negative ion states. Moreover, dramatic effects due to excess photon detachment have been observed yielding additional information on the dynamics of these highly correlated systems