Using tiny particles of gold, researchers from the University of Cambridge have concentrated light to smaller than a single atom. By focusing the light to just under a millionth of a meter, the scientists have a "magnifying glass" that reveals individual chemical bonds within molecules.

The achievement supports new ways to study the interaction of light and matter, including the possibility of making the molecules in the cavity undergo new sorts of chemical reactions. Such molecular transformation could enable the development of entirely new types of sensors.

In collaboration with European colleagues, the team used highly conductive gold nanoparticles to make the world’s tiniest optical cavity, one only big enough for a single molecule. The cavity – called a ‘pico-cavity’ by the researchers – consists of a bump in a gold nanostructure, and confines light to less than a millionth of a meter.

To create the pico-cavities, the researchers placed laser light on the sample. The team could then watch single atom movement in real time.

With the light-catalyzed chemical reactions, complex molecules could be built from smaller components. The University of Cambridge innovation enables opto-mechanical data storage devices that allow information stored in the form of molecular vibrations, to be written and read by light.

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