FROM WANNIER DOUBLY EXCITED STATES TO THRESHOLD IONISATION

A M Loughan$^\ast$ and D S F Crothers$^\ast$

$^\ast$Theoretical and Computational Physics Research Division,
The Queens University of Belfast BT7 1NN, UK.

We present the details and results of the application of Crothers'
semiclassical wavefunction$^1$ to the below threshold problem
of doubly excited states for total angular momentum $L=0,1$ and $2$. Analytic
continuation of this theory allows us to address both the singlet and
triplet threshold ionisation problem for which we present the spin asymmetry and
 absolute
triple differential cross sections. The principal target in both studies
is atomic or ionic helium.