Oxygen adsorption by supported size-selected copper clusters: Substrate effects

We report effect of substrate on the oxygen adsorption by the supported copper clusters. Deposition of preformed size selected Cu nanoclusters at very low energy is performed with ultra high vacuum compatible magnetron based gas aggregation type nanocluster source. X-ray photoelectron spectroscopy (XPS) study on as-deposited supported copper clusters on different substrates as well as on samples after air exposure in the laboratory atmosphere shows a growth in oxygen adsorption with time of exposure. Oxygen adsorption (chemisorptions) in air leads to change in oxidation state of copper with a mixture of Cu(I) and Cu(II) state easily. Time scale of formation of Cu(II) is found to depend on the substrates. Morphological characterizations of the supported clusters were performed using scanning electron microcopy and atomic force microscopy.