[en] The role played by the projectile in generating both characteristic and non-characteristic x-rays during argon ion bombardment of silicon and silicon carbide is examined. This involves an investigation of the effect of projectile build-up in these targets, and some high resolution spectral examination of the ArL x-rays. It emerges that Ar → Si collisions are mainly responsible for the non-characteristic x-rays; the dominant mechanism at the energy investigated is a double scattering process, although recoils also play a role in the Ar → Si system. The differential cross-sections for non-characteristic x-rays produced during C → C collisions have been measured over the energy range 40 → 280 keV. This work demonstrates a gradual levelling off of these cross-sections and also highlights the appearance of x-rays having energy greater than the united atom limit, arising from a collision broadening effect. (6 figs, 18 refs) (U.S.)