Individual silver nanoclusters can emit photoactivated fluorescence, Robert M. Dickson and coworkers at Georgia Institute of Technology have discovered [Science, 291, 103 (2001)]. The clusters are formed by the photoreduction of Ag₂O on the surface of extremely thin (less than 20 nm) silver films. Illumination of the thin films with wavelengths shorter than 520 nm results in multicolored fluorescence, with nanoparticles being activated individually. After particles have been photoactivated, they fluoresce under both blue and green excitation. Continuous excitation with blue light results in "blinking" or intermittent fluorescence. When illuminated with green light, the particles emit brighter, more stable red fluorescence. The researchers say that, because each particle is individually photoactivated, the films could eventually be used for data storage, with the data being written with blue light and nondestructively read with green light.

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