Small Copper Clusters in Ar Shells: A Study of Local Structure

Small copper clusters embedded in argon shells were obtained using the pick-LIP technique. The clusters were analyzed using X-ray absorption near-edge spectroscopy (XANES) measured at the Cu L-23-edge. Theoretical interpretation of the experimental spectra has been performed using full-potential finite difference method simulations and density functional theory (DFT) to optimize the geometry of the clusters. As a result, it was found that the icosahedral Cu-13 nanocluster with the geometry optimized by DFT produces theoretical Cu L-23-XANES similar to the experimental one, whereas the theoretical XANES of the cuboctahedral cluster differs from that of the experimental. The bonding energy for the icosahedral cluster obtained by the present DFT study has a higher absolute value than that for the cuboctahedral cluster, thus also supporting the higher stability of the icosahedral Cu-13 nanocluster.