The Structure of Triply Excited, Negative-Ion Resonances in the Autoionizing Region of Helium

Abstract

The formation and decay of the two lowest-lying, triply excited He- resonances in the autoionizing region of the helium spectrum (57-60 eV) have been studied by measuring electron-impact excitation functions for the n = 2 singly excited states of helium as a function of electron scattering angle. These results offer unambiguous confirmation of the classification of these states as He- 2s 2p22P and 2s2p22D, respectively. Furthermore, the observation of the relative strengths of the decay of these features into the various final states enables some speculation as to the structure of the three excited electrons.