Experimental observation of initial-state effects in photo-double-ionization of Ne 2s

The triple-differential cross-sections (TDCS) of the He 1s ² and Ne 2s ² shells at the same excess energy above the threshold in the equal energy sharing conditions were investigated. The symmetries of both the residual ion and electron pair in the final state, ¹S ^e and ¹P ⁰, as well as the kinetic energy of the ejected electrons were found to be the same. It was observed that the shape of the Ne TDCS displays differences can be explained by the intershell ground-state correlation in Ne as supported by convergent close coupling (CCC) calculations with He-like final state and two different Ne ground states. The results show that the Ne TDCS are qualitatively different from the He ones.