Position and widths of autoionising states in the helium isoelectronic sequence above the N=2 continuum

Abstract

Energies and widths of autoionising states in the helium isoelectronic sequence (Z=5-10) converging to the n=3 and n=4 hydrogenic thresholds are computed. States of symmetry ¹S^e, ¹P^o, ¹D^e are considered. Using the Feshbach formalism the eigenvalues of QHQ are calculated by the truncated diagonalisation method of Altick and Moore (1965) or Lipsky et al. (1977) and the continuum functions by the static exchange approximation. The author computes both total widths and partial widths associated with the various open channels.