Cross sections forK- andL-shell excitation in slow-ion—atom collisions

Absolute cross sections for Auger-electron production were measured for the target atom Ar bombarded by ${\mathrm{B}}^{+}$, ${\mathrm{C}}^{+}$, ${\mathrm{N}}^{+}$, ${\mathrm{O}}^{+}$, and ${\mathrm{Ne}}^{+}$ ions at energies from 50 to 600 keV. Cross sections for $L$-shell excitation of the target atom and the $K$-shell excitation of the projectiles were deduced. The sum of the $L$- and $K$-shell excitation cross sections are found to increase monotonically with decreasing nuclear charge of the projectiles. The data are interpreted in terms of adiabatic molecular orbital (MO) diagrams. Evidence is found for electron promotion via the $3d\sigma$ MO being the dominant mechanism which is responsible for the inner-shell vacancy production.