Absolute core-level binding energy shifts between atom and solid: The Born-Haber cycle revisited for free nanoscale metal clusters

Core-level binding energy shifts between the free atom and corresponding large clusters, the latter closely approximating the infinite solid, have been experimentally derived for several elemental metals. The cluster core-level binding energies in question have been determined relative to the vacuum level using synchrotron-based photoelectron spectroscopy. As expected, the experimental shift values show reasonable agreement with those calculated using the thermochemical Born-Haber cycle approach. The largest uncertainty factors defining the discrepancies between the experiment and the model, such as the difference in the multiplet structure of free atoms and the solid, the in some cases indirectly established cluster work functions, and the metal solvation energy, are discussed.