The first interpretation of giant resonance behavior in the inelastic scattering of electrons from heavy ions is reported for the electron-impact double ionization of ${\mathrm{Cs}}^{+}$. A discussion of the partial-wave potentials and phase shifts leading to this phenomenon is presented along with results of several distorted-wave calculations of the cross section. The theoretical cross sections are in good agreement with the results of a crossed-beam measurement.

• Received 21 April 1986

DOI:https://doi.org/10.1103/PhysRevLett.56.2618