Importance of Distortion in Inelastic Encounters Between Heavy Systems

It is shown that distortion may have a considerable influence on excitation and ionization cross sections even at quite high energies. Using an impact parameter treatment detailed calculations are carried out on the collision processes H + + H(1s) → H + + H(2s) and He 2+ + H(1s) → He 2+ + H(2s). The introduction of allowance for distortion is found to lead to much smaller cross sections at low and moderate energies.