Shining green laser light on a gold nano-antenna enhances its intensity

Green light on gold atoms.

Atoms and molecules are several times smaller than the wavelength of visible light. Hence, it is quite challenging to gather information about their dynamics, especially when embedded within larger structures.

In order to address this limitation, metallic nano-antennas are under development. These nano-antennas concentrate light into a tiny volume to dramatically enhance any signal coming from the same nanoscale region.

Now, EPFL scientists have discovered that shining green laser light on a gold nano-antenna enhances its intensity till it knocks gold atoms out of their equilibrium positions. While this is happening, it also maintains the integrity of the overall structure.

The gold nano-antenna also amplifies the very faint light scattered by the newly formed atomic defects, making it visible to the naked eye.

This nanoscale dance of atoms can thus be observed as orange and red flashes of fluorescence, signatures of atoms undergoing rearrangements.

Professor Christophe Galland at the School of Basic Sciences said, “Such atomic-scale phenomena would be difficult to observe in situ, even using highly sophisticated electron or X-ray microscopes, because the clusters of gold atoms emitting the flashes of light are buried inside a complex environment among billions of other atoms.”

Wen Chen, the study’s first author, said“The unexpected findings raise new questions about the exact microscopic mechanisms by which a weak continuous green light can put some gold atoms into motion. Answering them will be key to bringing optical nano-antennas from the lab into the world of applications – and we are working on it.”

Journal Reference:
  1. Wen Chen, Philippe Roelli, Aqeel Ahmed, Sachin Verlekar, Huatian Hu, Karla Banjac, Magalí Lingenfelder, Tobias J. Kippenberg, Giulia Tagliabue, Christophe Galland. Intrinsic luminescence blinking from plasmonic nano junctions. Nature Communications 21 May 2021. DOI: 10.1038/s41467-021-22679-y

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