Initial- and final-state effects on screening and branching ratio in 2p x-ray absorption of size-selected free 3d transition metal clusters

A comprehensive study of size-dependent initial- and final-state effects in 2p x-ray absorption of free, homonuclear 3d transition metal clusters from titanium through nickel in a size range of 1-200 atoms is presented. From atom to bulk the 2p arrow right 3d excitation in 3d transition metals shifts to higher photon energy, which can be explained by increasing valence electron delocalization in the initial state. A cluster-size-dependent decrease of the L sub(2.3) branching ratio at a constant 2p spin-orbit splitting can be attributed to core-hole screening effects for all investigated 3d transition metal clusters. For small manganese cluster ions, highly localized 3d orbitals with ferromagnetic spin coupling and a filled 3d majority spin subband are suggested by the experimental 2p x-ray absorption spectra.