This week, US researchers announced that they had developed the darkest material on Earth, a substance that is more than 30 times darker than the carbon substance used by the US National Institute of Standards & Technology as the current benchmark of blackness. According to Reuters, the new substance, which absorbs 99.9% of light, is composed of carbon nanotubes standing on end. It has a total reflective index of 0.045%, compared to 5% to 10% for basic black paint.
Pulickel Ajayan, who led the research team at Rice University, said that the material gets its blackness from three factors:
- It is composed of carbon nanotubes, tiny tubes of tightly rolled carbon that are 400 times smaller than the diameter of a strand of hair. The carbon helps absorb some of the light.
- These tubes are standing on end, much like a patch of grass. This arrangement traps light in the tiny gaps between the “blades.”
- The researchers have also made the surface of this carbon nanotube carpet irregular and rough to cut down on reflectivity.
Below is a photo of the new material. The nanotube material is in the center; at the left is the NIST’s reflectance standard; at the right is a piece of glassy carbon.
Photo: Shawn-Yu Lin, RPI via Reuters
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