  Partial autoionization rates of doubly excited one-dimensional helium in the
collinear Zee and eZe configuration are obtained by means of the complex
rotation method. The approach presented here relies on a projection of
back-rotated resonance wave functions onto singly ionized $\textrm{He}^{+}$
channel wave functions and the computation of the corresponding particle
fluxes. In spite of the long-range nature of the Coulomb potential between the
electrons and the nucleus, an asymptotic region where the fluxes are stationary
is clearly observed. Low-lying doubly excited states are found to decay
predomintantly into the nearest single-ionization continuum. This approach
paves the way for a systematic analysis of the decay rates observed in
higher-dimensional models, and of the role of electronic correlations and
atomic structure in recent photoionization experiments.

Atomic Physics