Magnetic-substate ionization of medium- and high-Z_t elements induced by proton impact

Magnetic-substate ionization of L₃-subshell and the consequent atomic alignment of molybdenum, cadmium, indium and gold ions are reported for proton impact with low incident velocity range (0.147∼0.232)v_L3, (0.124∼0.196)v_L3, (0.120∼0.191)v_L3, (0.067∼0.107)v_L3, respectively. Here, v_L3 is the classical orbital velocity of an electron in the L₃-subshell of the target atom. It is demonstrated that the L_β2 and L_α X-ray lines present spatially non-isotropic emission. Coster-Kronig calibration factors as well as anisotropy coefficients are calculated to derive the alignment parameter A₂₀. Unifying A₂₀ and the cross section σ_L3 in direct ionization, a novel methodology to determine the cross sections [Formula presented] and [Formula presented] for magnetic substate ionization is introduced. The results manifest that both cross sections exhibit positive correlation with the incident energy and inverse correlation with atomic number of the target. The cross section [Formula presented] is found to be greater than [Formula presented], and the tendency of the ratio [Formula presented] varies regularly and gradually as the atomic number increases for the four targets. Particularly, it also implies that the ionization cross section for high-Z_t targets exhibits a more remarkable increase rate with the increase of incident energy. Experimental results are well understood by taking account of probability density distribution of the orbital electrons.