The oxidation of Co nanocolumns grown by the glancing angle deposition technique was studied ex situ using scanning tunneling microscopy and spectroscopy. The normalized conductance (dI/dV)/(I/V) of a single nanocolumn shows a nonoxidized Co peak at about -0.7 eV corresponding to the 3d valence electrons which was absent in the conventional film. It is argued that a retardation of the oxidation occurred in the Co nanocolumn due to the lack of grain boundaries in the isolated nanocolumns. (C) 2002 American Institute of Physics. References: 16
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