Hidden crossing superpromotion mechanism for 2p sigma-vacancy creation in heavy ion-atom collisions

It is shown that the transitions along the S-p sigma- and Q(3p sigma)-superseries of hidden crossings in a heavy ion-atom collision system (Z(1), Z(2) > 25-30) form a dominant mechanism for the 2p sigma vacancy production at low reduced relative collision velocities. The 2p sigma-vacancy creation probability as a function of the impact parameter, calculated within this model for several collision systems and collision energies, agrees well with the experimental observations. A scaling relationship is derived for the 2p sigma-vacancy creation cross section which adequately describes the experimental data for charge-symmetric heavy ion-atom systems.