Kx-ray production in single collisions of chlorine and sulfur ions

Cl $K$ x-ray-production cross sections have been measured in single collisions of 0.1-1.5-MeV/amu Cl ions with gas targets of He, ${\mathrm{N}}_2$, Ne, Si${\mathrm{H}}_4$, ${\mathrm{H}}_2$S, HCl, Ar, Kr, and Xe. Cross sections for Ne $K$, Si $K$, S $K$, Ar $K$, Kr $L$, and Xe $L$ x-ray production and yields for Xe $M$ x rays were also obtained. Similar measurements for both Cl and S ions were made at one velocity as a function of projectile charge state $q$ for $5\le q\le 11$. Except at the highest energies, projectile $K$ x-ray-production cross sections are nonmonotonic as a function of target atomic number $Z_2$. Anomalously high target and projectile cross sections occur in the symmetric region: $Z_2\simeq 17$. For all x-ray lines, the cross sections show an increase with increasing $q$ at constant projectile velocity, with the rate of increase being greatest in the symmetric region. The experimental results indicate the importance of one-step molecular processes suggested by Meyerhof in producing $K$ vacancies. The $2p\sigma -2p\pi$ transition may be of importance when initial $2p$ vacancies are carried into $K$-vacancy-producing collisions. The large cross sections for both target and projectile in nearly symmetric collisions gives evidence for $K$-vacancy transfer between collision partners.