[en] We have observed for the first time a pronounced increase of the molecular-K-x-ray production as a function of projectile charge state in 32-MeV S + Ar (gas target) collisions. The results are interpreted as evidence for strong excitation of 1ssigma electrons into empty high-lying bound states. A comparison of this gas-target system and the solid-target systems Cl + Cl establishes unambiguously the predominance of one-collision processes for molecular-K-x-ray production