Distinguishing the effect of crystal-field screening from the effect of valence recharging on the 2p _3/2 and 3d _5/2 level energies of nanostructured copper

Incorporating the recent bond order-length-strength correlation mechanism [C.Q. Sun, Phys. Rev. B 69 (2004) 045105] to the size dependence of Auger photoelectron coincidence spectra of Cu nanoparticles with and without being passivated has enabled us to gain quantitative information about the 2p and 3d level energies of an isolated Cu atom and their shift upon bulk formation. The developed approach also enabled us to discriminate the effect of crystal-field screening from the effect of valence recharging (due to surface passivation and substrate-particle interaction) on the binding energies to the electrons at different energy levels of a specimen.