Light makes molecule shine

Researchers from Kyushu University in Japan have constructed a fluorescent molecule that can be repeatedly switched on and off.

The molecule could eventually be used to store data. In such a storage device, the two states of the molecule - giving off light or not giving off light - would represent the ones and zeros of digital information. If a way can be found to switch individual, closely-packed molecules on and off, fantastic amounts of information could be stored in very small spaces.

The researchers' molecule is a fluorescent compound that switches on and off by changing shape in the presence of certain types of light. Key to the compound's potential usefulness is that it remained stable even when switched repeatedly. Many fluorescent compounds are fragile.

The shape of the fluorescent form of the molecule is a split ring. Shining three seconds of ultraviolet light on the molecule closes the ring and prevents the molecule from giving off light. Shining visible light on the molecule for 10 seconds opens the ring again. The work appeared in the December 18 issue of Nature.