For a long time, researchers thought blacker than black would not work. For example, the known Vantablack absorbs 99.96 percent of the light falling on it.
But now, two scientists at the Massachusetts Institute of Technology (MIT) in Boston have made a material that is a little darker than anything that has ever been. The development of Kehang Cui and Brian Wardle swallowed 99.995 percent of the light, the researchers write in a recent study. Such future materials should eventually find practical applications, for example in space.
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The excellent absorption properties of materials such as Vantablack result from the special surface structure of the material. Numerous nanotubes made of carbon are arranged side by side. These become the trap for the rays of light. Because in the tubes, the light strays to a certain extent and can no longer escape.
In the lab, Cui and Wardle were actually looking for ways to make such nanotubes easier to build on an aluminum foil to measure their thermal and electrical capabilities. The process is hampered by an oxide layer created by the influence of oxygen in the air. They achieved better results when they treated the aluminum with a salt solution that removed the oxide layer. Subsequently, the tubes grew in an oxygen-free environment. Finally, measurements showed that their method had improved the absorption properties. Why this is so, the researchers can not say exactly.
Although the human eye can not perceive the difference to previous surfaces. But he was quite relevant to research, says a statement by MIT.
Because the hunt for the blackest black is not only a competition among vain researchers, it is also about future development. So the new materials are to improve telescopes or cameras, because stray light causes less interference. This makes measurements with highly sensitive space telescopes even more accurate.
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One billion nanotubes per square centimeter
Vantablack was developed in 2014 in Great Britain by Surrey Nano Systems. A surface of only one square centimeter of the substance consists of one billion nanotubes. Due to the strong absorption of light, the human eye can not recognize any shape properties of structures that are coated with the material. This makes it interesting for the military to improve camouflage.
This becomes clear in an art event in which the MIT researchers have now taken part and with which they presented their development: for an exhibition in New York, they covered a precious diamond with their material. This gives visitors the impression that they are looking at nothing.