Oscillator strength electron angular distribution

In practice one either measures the angular distribution of the scattered electrons and plots f(K) as a function of K, and extrapolates the resulting curve to K = 0 and fits this curve to the known optical oscillator strength /(O), or one carries out the experiment at high impact energy and low (preferably zero) scattering angle and assumes that the optical limit has been achieved. 

The calculations include, as said previously, overlaps, conditional probability distributions of the electron probability densities, and these observables oscillator strengths, quadrupole moments (for states with total angular momentum quantum numbers of 1 or more) and expectation values (pi p2)/( pi i>2 )- (Distributions of this last quantity have also been computed, in preparation for two-electron ionization experiments by electron impact, but are not reported here.) We can proceed to summarize these indicators and then examine them and ask how well each model performs. 

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