Characterization of Charge States of Energetic Ions in Solids from AssociatedKX-Ray Production

The strong projectile—charge-state dependence of $K$ x-ray production in gases establishes a charge-state scale for ions penetrating solids. Si $K$ x-ray cross sections in gaseous Si${\mathrm{H}}_4$ were compared to those in solid Si for 40-MeV O (6+ to 8+) and 86-MeV Ar (6+ to 16+) projectiles. For Ar an effective charge of 11 ± 1 is found compared to an emergent charge of 14.8 ± 0.5. The result is discussed in terms of alternate models for steady-state excitation in solids.