Nonlocal screening effects in 2px-ray photoemission spectroscopy of NiO (100)

We report on the layer thickness dependence of Ni 2p core-level line shapes of epitaxially grown, in a layer-by-layer fashion, NiO on a single-crystal MgO (100) substrate. The results demonstrate the sensitivity of the core-level line shape to the nearest as well as next-nearest-neighbor coordination number. The results are consistent with a recent theoretical study of nonlocal screening effects. {} 1996 The American Physical Society.