Measurement of n- and l-resolved State-selective Charge Exchange in Ar8+ Collision with He

• Published in: The Astrophysical journal Vol. 933; no. 2; pp. 207 - 211
• Main Authors: Xia, Z. H., Ren, B., Zhang, R. T., Wei, L., Han, J., Meng, T., Wang, J., Ma, P., Zhang, Y., Tu, B., Xiao, J., Yao, K., Zou, Y., Zhu, X. L., Guo, D. L., Ma, X., Wei, B.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.07.2022; IOP Publishing
• Subjects: Absorption cross sections; Angular momentum; Astrophysics; Atomic data benchmarking; Atomic physics; Charge exchange; Charge exchange recombination; Collision processes; Empirical analysis; Ion charge; Recoil ions; Scaling laws; Soft x rays; Spectroscopy; X-ray emissions
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac76c3

The state-resolved capture cross sections for principal n and orbital angular momentum l play an important role in modeling soft X-ray emissions induced by charge exchange for many astrophysical environments. However, the empirical and semiclassical theories used to produce these data of n- and l-resolved state-selective capture have not been well tested. Using the cold target recoil ion momentum spectroscopy apparatus at Fudan University, we perform a series of measurements of Ar8+ ion charge exchange with He in the collision energy range from 1.4 to 20 keV u−1. We find that electrons are mainly captured in the n = 4 state of Ar7+ ions. This agrees with the prediction of the scaling law for n capture. Moreover, the relative cross sections are reported for 4s-, 4p-, 4d-, and 4f-resolved state-selective capture. The often used analytical l distributions in the astrophysical literature are evaluated by comparing to the measurements.