Extremely thin films of silver oxide possess a remarkable property. If you selectively expose them to blue light, the exposed areas gain the ability to fluoresce. But the silver only glows when the activated areas are hit with a longer wavelength light--for example, in the green or yellow range. This fluorescence occurs without any destruction to the film and suggests applications in optical data storage and flat-panel displays.
The next challenge is to learn how long the activated areas retain the ability to give off light. "We are excited that it seemed to show absolutely no degradation after two days," says lead researcher Robert Dickson of the Georgia Institute of Technology.
Dickson explains that shining light with a wavelength of less than 520 nanometers on the silver-oxide thin film switches on the fluorescing ability by converting silver oxide to pure silver, which then glows brightly when exposed to light with a wavelength of greater than 520 nanometers.
What's more, Dickson noticed individual silver particles fluorescing in multiple colors. If the colors can be controlled, each data point could conceivably store more than one bit of information, allowing significantly higher-density storage than is possible with current optical memory media.