Measurement of n- and l-resolved State-selective Charge Exchange in Ar<sup>8+</sup> Collision with He
Zihan Xia, Baihui Ren, R. T. Zhang, L. H. Wei, Jie Han, Tao Meng, J. Wang, Pufang Ma, Yu Zhang, B. Tu, Jun Xiao, Ke Yao, Yu Zou, Xiaolong Zhu, Dalong Guo, X. Ma, B. Wei
Abstract
Abstract 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 Ar 8+ 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 Ar 7+ ions. This agrees with the prediction of the scaling law for n capture. Moreover, the relative cross sections are reported for 4 s- , 4 p- , 4 d- , and 4 f -resolved state-selective capture. The often used analytical l distributions in the astrophysical literature are evaluated by comparing to the measurements.