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Exciton

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11:30am, May 2, 2014

ON THE MOVE  An exciton, illustrated here, transfers energy to an electron.

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Getting excited can kick a person’s energy to a higher level. At the nanoscale, strange almost-particles called excitons do the same trick.

In a crystal, thin film or even some liquids, an incoming particle of light can slam into an electron, bumping it to a higher energy level and leaving a hole at the energy level where the particle had been. The exciton is the excited electron paired with the resulting hole and can move energy in two ways: by physically hopping to a new molecule or transferring energy almost like an antenna transmitting a signal. Either way, the movement is quick, with the longest-lasting exciton existing for just a few milliseconds.

Even though excitons don’t last long, scientists were recently able to make images of how the quasiparticles moved (SN Online: 4/16/14). Investigating excitons’ ability to kick around nanoscale energy could improve scientists’ understanding of photosynthesis and lead to better solar cells, LEDs and semiconductor circuits.

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