Green light on gold atoms

Credit: Nicolas Antille, www.nicolasantille.com - Scientists at EPFL discover that laser-driven rearrangement of just a few gold atoms inside nanoscale antennas can be observed by the naked eye. Image: Plasmonic nano-antennas fabricated at EPFL: gold nanoparticles are deposited on a gold film covered with a layer of molecules. Light emission from defects near the film surface is strongly enhanced by the antenna effect, enabling its detection. Credit: Nicolas Antille (www.nicolasantille.com). Because individual atoms or molecules are 100 to 1000 times smaller than the wavelength of visible light, it is notoriously difficult to collect information about their dynamics, especially when they are embedded within larger structures. In an effort to circumvent this limitation, researchers are engineering metallic nano-antennas that concentrate light into a tiny volume to dramatically enhance any signal coming from the same nanoscale region. Nano-antennas are the backbone of nanoplasmonics, a field that is profoundly impacting biosensing, photochemistry, solar energy harvesting, and photonics. Now, researchers at EPFL led by Professor Christophe Galland at the School of Basic Sciences have discovered that when shining green laser light on a gold nano-antenna, its intensity is locally enhanced to a point that it "knocks" gold atoms out of their equilibrium positions, all the time maintaining the integrity of the overall structure.