Soft X-ray emission spectroscopy of Co nanoislands on a nitrogen-adsorbed Cu(0Â 0Â 1) surface

Valence electronic states of mono-atomic layer Co on the nitrogen adsorbed Cu(0 0 1) surface are studied by soft X-ray emission spectroscopy. The L3 resonant X-ray emission spectrum can be divided into two components; one is that emitted from the single-layer Co islands and the other is that from more than 2 ML thick Co films. The former has a narrower width and a lower binding energy than the latter. These results are in good agreement with the 3d density of states calculated by a first-principles method for single- and double-layer Co films on Cu(0 0 1), and clearly demonstrate narrowing of the 3d states in the single-layer.