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Synthesis of Small Atomic Copper Clusters in Microemulsions

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journal contribution
posted on 21.07.2009 by Carlos Vázquez-Vázquez, Manuel Bañobre-López, Atanu Mitra, M. Arturo López-Quintela, José Rivas
We report evidence of the formation of small atomic copper clusters, Cun, by the microemulsion technique, and how their size can be controlled by adjusting the percentage of the reducing agent used. Copper clusters were characterized by UV−visible spectrophotometry and atomic force microscopy. Photoluminescent copper clusters, Cun, with n ≲ 13, can be obtained using very low percentages of the reducing agent (<10% of the stochiometric amount). Photoluminescent clusters disappear for larger percentages of reducing agent, giving rise to larger copper clusters (0.8−2.0 nm), showing a red-shift of their UV−visible absorption bands as they grow in size. Finally, by using near stoichiometric amounts, nanoparticles of 2.9 ± 1.1 nm in size, displaying the characteristic plasmon band, can be obtained.