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

TL;DR

This study measures n-resolved charge exchange cross sections for Ne(8,9)+ ions colliding with He and H2, compares results with theoretical models, and assesses their implications for astrophysical soft X-ray emission modeling.

Contribution

It provides experimental n and l resolved charge exchange cross sections for Ne ions with He and H2, validating and comparing them with multichannel Landau Zener calculations.

Findings

MCLZ calculations agree well with measurements for dominant n capture in Ne-He collisions.

Experimental data supports the use of MCLZ for modeling charge exchange in astrophysical contexts.

Calculated soft X-ray emissions align reasonably with experimental results, especially when using MCLZ-based models.

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 H2 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 Ne8+ and He by considering the radiative cascade from the excited Ne7+ ions. Reasonable agreement is found in comparison to the measurement for even and separable models, and MCLZ calculations give results in a better agreement.