by an intense absorption in the visible region, which enhances the utility of these species for the development of completely optical devices. The wavelength of this surface plasmon resonance (SPR) band depends on the size and shape of the nanoparticles as well as their interactions with the surrounding medium. The presence of this band enhances the utility of gold nanoparticle as building blocks for devices for data storage, ultrafast switching, and gas sensors. Whilst plasmonic gold nanoparticles only exhibit electric moments, clusters of such particles can exhibit magnetic moments making them of great interest for use in optical metamaterials Gas-phase clusters Evidence has been presented for the existence of hollow golden cages with the partial formula with n = 16 to 18. These clusters, with diameter of 550 picometres, are generated by laser vaporization and characterized by photoelectron spectroscopy. Using mass spectrometry, the unique tetrahedral structure of has been confirmed. Catalysis When implanted on a surface, gold clusters catalyze oxidation of at ambient temperatures. Similarly gold clusters implanted on can oxidize at temperatures as low as 40K. Catalytic activity correlated with the structure of gold nanoclusters. A strong relationship between energetic and electronic properties with size and structure of gold nanoclusters. See also Thiolate-protected gold cluster Bismuth cluster References Further reading External links Cluster chemistry Gold compounds