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03/28/2024 08:11:27 am

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Newly Discovered 'Plasmoelectric Effect' Converts Light into Electricity

Artist's impression of the plasmoelectric effect

(Photo : Amolf/Tremani) Artist's impression of the plasmoelectric effect. An ultrasensitive needle measures the voltage that arises if a laser illuminates a metal nanocircuit consisting of a square matrix of miniscule holes in a thin gold film

Researchers from the California Institute of Technology and the FOM Institute AMOLF have discovered a new method for the production of electrical potentials by using minute metal nanocircuits to effectively capture light and convert it into an electrical potential of 100 millivolts.

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The AMOLF-Caltech team has named the newly discovered effect the "plasmoelectric effect."

"This is an entirely new way of converting light into electricity," Albert Polman, leader of the AMOLF part of the team, said. "We have now demonstrated that an electrical voltage can be generated; the next step is to see whether we can also collect electrical current and generate electrical power."

Small particles of precious metals such as gold, silver and copper have been noted to emit colorful spectrums when they are illuminated. A well-known example of the phenomena is stained-glass windows in old buildings and churches in which the colors are produced by the metal nanoparticles that have been integrated in the glass. The shining light on the small particles are converted into plasmons, which are oscillations of the free electrons of the metal.

The oscillations result in strong absorption of light and its diffraction into particular colors of the spectrum.

The team investigated the process of light absorption in synthetically manufactured metal nanostructures by creating them with the aid of advanced clean room methods. They illuminated nanospheres of gold with light and found that a negative electrical potential arose when blue light was used to light them. When red light was used to illuminate the nanospheres on the other hand, they were met with a corresponding positive potential.

The scientists measured the electrical voltage using an ultrasensitive needle that was placed above the nanoparticles that were being illuminated and were able to receive a hundred millivolts.

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