Description:

Gold rings are suddenly exciting for a whole new reason, and it has nothing to do with the price of gold or trends in marriage. Moreover, in this case, smaller rings are better.

Gold nanorings of about 60 nm radius have unique optical and electromagnetic properties that can be "tuned" by varying the ratio of the ring radius and wall thickness.  Researchers found a way to synchronize the energy of the incoming light and the pool of electrons in the metal ring, so that they "resonate" on the same wavelength.

This resonance creates a strong and uniform electromagnetic field that oscillates inside the ring cavity. The figure depicts the field within and around a ring with a radius of 60 nm and a wall thickness of 10 nm. The colors indicate the field strength, ranging from blue (weak) to green and yellow (strong and uniform) to red (very strong). The arrows indicate the direction of the field created by the pool of excited electrons.

The ring cavity could therefore be a useful container for experiments in which molecules are tested with light.  For example, researchers study the chemical bonds in biomolecules like proteins by probing them with lasers and detecting how much of the light is absorbed and re-emitted at specific frequencies. By conducting such experiments inside a nanoring, researchers could obtain amplified infrared signals and clearer results.

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