We have observed X-ray spectra for 20-2720 keV Ar ions in charge states fro
m 4 through 17 impacting on an SiO2 surface at 60 degrees from normal incid
ence. Besides x-rays from the K-shell filling in the case of Ar17+, We obse
rve characteristic silicon K-shell radiation. The intensity of this radiati
on is analysed in terms of x-ray fluorescence and vacancy transfer in close
atomic collisions.