X-ray transitions between correlated many-electron quantum states

The projectile energy dependence of apparent two-electron, one-photon x-ray transitions is determined from x-ray spectra resulting from collisions of nickel ions with thin nickel targets. Hartree-Fock energy calculations show that the observed projectile energy dependence can be attributed to the production of $L$-shell vacancies. It is also demonstrated that these transitions are fundamentally many-electron processes which cannot be described in terms of independent-particle models alone. Theoretical transition probabilities based on the non-closed-shell many-electron theory of Sinano$\stackrel{\mathrm{̌}}{\mathrm{g}}$lu yield a $K{\alpha }^h$ ($K\alpha$ hypersatellite) to $K\alpha \alpha$ branching ratio for nickel of 6700.