State-selective single- and double-electron capture processes in slow C4++He, Ne, Ar and Xe collisions

Abstract

The reaction mechanism responsible for single capture in slow ( approximately=500 eV) C4++Ne, Ar, Xe collisions and for double capture in slow ( approximately=500eV) C4++He, Ne collisions are identified through translational-energy-gain measurements. Double capture to excited projectile states is observed. The role of target excitation in electron capture processes has been investigated for single as well as for double capture. Moreover, the validity of the Wigner spin conservation rule is tested to some extent. For each process identified, a lower limit for the cross section is obtained, and the scattering angle and the kinematic shift are examined. A qualitative comparison of the measured cross sections with the Landau-Zener model is made. The influence of beam contaminations (metastables and H3+) is discussed.