A phenomenon of partial localization of core holes has been discovered. Green＇s function calculations on a linear NiN2 cluster used as a model of the weak chemisorption N2/Ni(100)c(2 x 2) system show that the N1s core holes in the ionized states of the cluster are not fully localized on the inequivalent nitrogen atoms as has been previously believed. The core holes in some of the states are considerably delocalized. This leads to distinct interference effects in angularly resolved X-ray photoelectron spectra.