Semi-classical uniform approximation in Penning ionization

The uniform approximation is used to evaluate the semi-classical S-matrix for Penning ionization. The energy spectrum of the electron ejected in the Penning process: He * (1s2s,2 3 S)+H(1s,1 2 S) to He(1s 2 ,1 1 S)+H + +e - ( epsilon ) is calculated numerically. The results compare favourably to quantal calculations.