Precise measurement of atomic alignment and magnetic sub-state ionization in gold by H+ and He2+ ions impact

Atomic alignment of Au ions with L3-subshell ionization by H+ and He2+ ions impact is reported for low incident velocity range, i.e., (0.06-0.11) for H+ and (0.04-0.08) for He2+ ions. Experimental results are compared with PWBA and SCA models. It is demonstrated that PWBA model cannot predict the measured values well for both projectiles. For SCA model, it can aptly anticipate the experimental outcomes when subjected to H+ impact., while it overestimates the measured alignment (absolute value) for He2+ ions impact. Discrepancies for He2+ ions impact are ascribed to utilization of the CK transition coefficients determined for single ionization, while multiple ionization occurring in the practical situation. Moreover, magnetic sub-state ionization cross sections σ(32,32) and σ(32,12) are determined with the measured alignment parameter A20, and the results are further explained by taking into account collision dynamics and spatial distribution of the m=0 and m=1 wavefunctions.