Qualitative Aspects of Resonances in Electron—Atom and Electron—Molecule Scattering, Excitation, and Reactions

TLDR

The paper offers a qualitative description of various resonant states in atoms and molecules. The authors suggest experiments to test the proposed ideas. A general quasistationary method, justified by the Feshbach technique, is introduced to calculate resonant state energies from intuitively chosen trial functions and is compared with existing calculations. The classification aids in explaining experimental phenomena and shows that atoms and molecules possess both single‑particle and core‑excited resonant states, mirroring nuclear physics.

Abstract

A qualitative description of various types of resonant states of atoms and molecules is given. The classification is seen to be useful in explaining and discussing experimental phenomena. It is found that, as in nuclear physics, atoms and molecules exhibit both single-particle and core-excited resonant states. A general quasistationary method is presented which can be used to calculate the energies of the resonant states from intuitively selected trial functions. The Feshbach technique is used for formal justification of this method, and the relation of the quasistationary method to other published resonance calculations is discussed. Experiments are suggested to test the ideas presented.