Gold-oxide-containing
nanoparticles have been produced in a range
of partial to full oxidation conditions, where the nanoparticle electronic
structure and stoichiometry have been characterized. Our results indicate
that with the increase of the oxidation degree in these nanoparticles
the gold oxidation state possibly changes from lower oxides with mono-
or divalent metal to the higher oxide with the trivalent gold. At
intermediate oxidation conditions our observations are consistent
with a radially segregated structure of such nanoparticleswith
the core containing mainly oxide and the surface covered with few
monolayers of metallic gold. These results have been possible to obtain
combining the vapor aggregation method for the nanoparticle fabrication
and synchrotron-based photoelectron spectroscopy for their characterization.
The deposition of the oxidized nanoparticles has showed that the species
assigned as containing lower oxide could be preserved in the landing
and then studied on a substrate for a limited time. The possible lower
oxide formation in nanoparticles is discussed in connection to the
enhanced catalytic activity of gold nanoparticles.