Interactions of Au cluster anions with oxygen

The oxygen adsorption on Au cluster anions consisting of 1, 2, 4, and 6 Au atoms was studied using ultraviolet photoelectron spectroscopy and density functional theory calculations. The mass of clusters was selected using a time-of-flight mass spectrometer. It was found that for the neutral clusters, oxygen was less activated with respect to the anionic clusters. The results indicate that the additional electrons in the anionic states of these Au clusters are crucial for the activation of the O-O bonding. The results also show that high chemical activities of even numbered Au nanoclusters result from the stabilization of molecular oxygen on negatively charged Au clusters.