Tuesday, May 17, 2022

Shining green laser light on a gold nano-antenna

A green light on gold atoms.

It is quite challenging to collect information about the dynamics of individual atoms or molecules as they are 100 to 1000 times smaller than the wavelength of visible light. This becomes extremely challenging, especially when they are embedded within larger structures. 

Scientists are trying to address this limitation by engineering metallic nano-antennas that concentrate light into a tiny volume to enhance any signal coming from the same nanoscale region dramatically. 

Now, scientists at EPFL 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, all the time maintaining the integrity of the overall structure. 

The gold nano-antenna amplifies the exceptionally faint light dissipated by the recently formed atomic defects, making it visible to the naked eye. 

Scientists observed the nanoscale dance of atoms in orange and red flashes of fluorescence. This dance signifies that atoms undergoing rearrangements. 

Professor Christophe Galland 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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