Molecular-orbital—K-vacancy production by direct impact in symmetric heavy-ion collisions

Using simple scaling laws based on the adiabatic approximation, Meyerhof and co-workers have compared experimental data on $K$-vacancy production cross sections for symmetric collisions of heavy atoms and ions, with ab initio calculations of cross sections for direct impact ionization of hydrogen atoms by slow protons, done in this laboratory. It is shown here that the relative magnitudes and energy dependences of such cross sections can be understood using a simplified model theory; dominant features are determined by the oscillatory exponential factors associated with momentum and energy loss by the heavy particles, rather than the electronic-coupling matrix elements.