In the world of computer data storage, it's all about making the digital bits occupy the smallest possible space. Researchers at the Georgia Institute of Technology have brought the concept to a whole new level-the nanoscale. By shining a blue laser beam onto an ultrathin film of silver oxide, a team led by Robert M. Dickson has created silver nanoclusters made up of only two to eight atoms each. Bits that small could give rise to optical discs holding thousands of gigabytes; today's best DVDs hold less than 10 gigabytes per side. The data is read by exposing the clusters to green light, causing them to fluoresce. Each cluster can be made to glow in a range of colors-not just the "on" and "off" of binary systems-opening the possibility of storing multiple bits in the same cluster simultaneously. So far, Dickson's group has used the fluorescent method to create nanoscale geometric images, such as the letter "L." Development of the technique for digital data storage will require further research to reveal why the material works as it does. One unresolved question: can the film be optically erased and rewritten?

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