The colors of the gold were changed to spell out “Nano Meta” – pictured here through a microscope. Credit: Southampton University
Scientists in Southampton, UK, are now able to change the color of gold, which could have applications in jewelry-making and security features.
The scientists published their findings in the Journal of Optics. The technique used by the scientists involves embossing tiny raised or indented patterns on the metal’s surface, altering the way that it absorbs or reflects light, thus changing its color to the naked eye.
A researcher uses one of the nano-fabrication machines used in the process. Credit: Southampton University
Nikolay Zheludev, who leads the nanophotonics and metamaterials research team at Southampton University, states that gold can now be made red or green or a multitude of other hues.
This process of nano-embossing could be applied to other metals, like silver or aluminum. The shape, height, and depth of the embossed patterns determines how light behaves when it hits the metals, and what colors are perceived.
The researchers state that this is the first time the visible color of metal has been changed in this manner. The colors of objects are determined by how light interacts with them. By embossing metals with patterns only around 100 nanometers across, the scientists have found a way to control which wavelengths of light the metal absorbs and reflects.
Reference: “Continuous metal plasmonic frequency selective surfaces” by Jianfa Zhang, Jun-Yu Ou, Nikitas Papasimakis, Yifang Chen, Kevin F. MacDonald and Nikolay I. Zheludev, 1 November 2011, Journal of Optics.
DOI: 10.1364/OE.19.023279
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