Charge state dependence of Si K x-ray production in solid and gaseous targets by 40 MeV oxygen ion impact

The yield of silicon K x rays induced by 2.5-MeV/amu oxygen ions in gaseous (SiH4) and amorphous solid targets was studied. For a gas density 7.4 x 1014 cm-2 the yield increases approximately exponentially with the charge state q of the projectile in the region q = 6, 7, 8. A similar, but smaller, trend is found for a 7 μg/cm2 solid target. At this beam energy the most probable oxygen charge state emerging from a solid Si target is O7+. The x-ray yield from the solid is in accord with the emergent charge state. (U.S.)