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The electronic states of cobalt nanoislands on a nitrogen-saturated Cu͑001͒ c͑2 ϫ 2͒-N surface have been investigated by means of x-ray absorption spectroscopy. In the case of low coverages, when the surface is covered by small Co islands, a shoulder structure in the Co L-edge absorption spectrum is observable at an energy about 3 eV higher than the absorption edge. By considering the unoccupied Co 3d state calculated by first-principles method, x-ray photoelectron spectra and the multiple scattering during the absorption process, the shoulder is attributed to the correlation among 3d electrons. The satellite intensity decreases with the increase in the Co island size. The perimeter Co atoms of the island are assigned as the origins of the correlation satellite by comparing its intensity with the morphology of the islands observed using scanning tunneling microscopy. The polarization dependent satellite intensity suggests that the electron correlation in the in-plane 3d orbital of the perimeter atoms is larger than that in the out-of-plane one.

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