Measurement of n-resolved State-selective Charge Exchange in Ne^(8,9)+ Collision with He and H₂

Abstract

Abstract Charge exchange between highly charged ions and neutral atoms and molecules has been considered as one of the important mechanisms controlling soft X-ray emissions in many astrophysical objects and environments. However, for modeling charge exchange soft X-ray emission, the data of n- and l -resolved state-selective capture cross sections are often obtained by empirical and semiclassical theory calculations. With a newly built cold target recoil-ion momentum spectroscopy (COLTRIMS) apparatus, we perform a series of measurements of the charge exchange of Ne (8,9)+ ions with He and H 2 for collision energy ranging from 1 to 24.75 keV/u. n -resolved state-selective capture cross sections are reported. By comparing the measured state-selective capture cross sections to those calculated by the multichannel Landau–Zener method (MCLZ), it is found that MCLZ calculations are in good agreement with the measurement for the dominant n capture for He target. Furthermore, by using nl -resolved cross sections calculated by MCLZ and applying l distributions commonly used in the astrophysical literature to experimentally derived n -resolved cross sections, we calculate the soft X-ray emissions in the charge exchange between 4 keV/u Ne 8+ and He by considering the radiative cascade from the excited Ne 7+ ions. Reasonable agreement is found in comparison to the measurement for even and separable models, and MCLZ calculations give results in a better agreement.