(n,l)−Subshell electron capture cross sections in collisions of C4+, N5+ and O6+ with atomic hydrogen

Abstract By means of VUV-photon spectroscopy we have determined absolute Subshell selective electron capture cross sections σ nl for collisions of helium-like carbon, nitrogen and oxygen ions with atomic hydrogen, in the velocity range 0.1–0.5 a.u. The atomic hydrogen beam target was produced by means of a radio-frequency discharge source, and absolutely calibrated by measuring atomic and molecular radiation in the visible region produced by electron impacts. For all systems studied we find that the total capture cross section ( σ t = Σ nl σ nl depends only weakly on the impact velocity, and is in good agreement with published results from other authors. In contrast to σ t , the Subshell selective cross sections σ nl are strongly velocity dependent. Our results are compared with recent calculations by Fritsch and Lin; the agreement is quite satisfactory.