We report narrow dielectronic-capture resonances decaying by double autoionization, observed for the first time in electron-impact ionization of ions. We also observe corresponding peaks in double and triple ionization leading us to postulate new processes where dielectronic capture is followed by triple or quadruple autoionization, respectively.

• Received 25 March 1988

DOI:https://doi.org/10.1103/PhysRevLett.61.70