Small copper clusters studied by x-ray absorption near-edge structure

The local structure of copper nanoparticles grown in organic solution by reducing Cu(II) hexafluoroacetylacetonate [Cu(hfac)2] was studied as-grown by the Cu K-edge x-ray absorption near-edge structure (XANES). Comparison of the experimental XANES spectra with reference materials indicated small copper clusters are formed by ligand-exchange with oleylamine and subsequent reducing by diphenylsilane. The multiple-scattering (MS) calculation for various model clusters consisting of 13–135 atoms suggests that small (13–19 atom) Cu clusters are stabilized without a large deformation.