Revealing of the new freedom of size: atomic energy levels, screening and charge transporting

Miniaturization of a solid forms a new freedom that is fascinating, which allows us not only to tune the physical properties of a solid but also enables us to gain information about the energy levels of an isolated atom and the effect of screening and charge transporting in reaction on the energy level shift, a calibration of crystal binding. Incorporating the recent bond order-length-strength correlation mechanism [Sun, Phys. Rev. B 69, 045105 (2004)] 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.