  A theory of the Post-Collision Interaction (PCI) is developed for the case
when an electron atom impact results in creation of two low-energy Wannier
electrons and an ion excited into an autoionizing state. The following
autoionization decay exposes the Wannier pair to the influence of PCI resulting
in variation of the shape of the line in the autoionization spectrum. An
explicit dependence of the autoionization profile on the wave function of the
Wannier pair is found. PCI provides an opportunity to study this wave function
for a wide area of distances
