Blackest Black: Researchers Create Darkest Substance on the Planet

A new substance developed by U.S. scientists is so that it absorbs more than 99.9 percent of all visible light. Now they want to find out if it can absorb invisible light as well, such as ultraviolet light, and other wavelengths such as radiation used in communications systems.

"If you could make materials that would block these radiations, it could have serious applications for stealth and defense," Ajayan said.

Made from tiny tubes of carbon standing on end, this material is almost 30 times darker than a carbon substance used by the U.S. National Institute of Standards and Technology as the current benchmark of blackness.

And the material is close to the long-sought ideal black, which could absorb all colors of light and reflect none.

"All the light that goes in is basically absorbed," Pulickel Ajayan, who led the research team at Rice University in Houston, said in a telephone interview. "It is almost pushing the limit of how much light can be absorbed into one material."

The substance has a total reflective index of 0.045 percent -- which is about 4 times darker than the nickel-phosphorous alloy that now holds the record as the world's darkest material, and over a 100 times darker than the paint on a jet black Corvette.

The Rice University researchers are likely to have their “world's darkest material” honored in the Guinness World Records. Indian-born Ajayan already holds the 2006 Guinness World Record as co-inventor of the smallest brush in the world.

Ajayan, who worked with a team at Rensselaer Polytechnic Institute in Troy, New York, said the material gets its blackness from several factors. Pure carbon is one of nature's darkest materials—think of the charred pieces of wood leftover from a campfire.

But their material is composed of tiny carbon nano-tubes, tightly rolled cylinders of carbon that are 400 hundred times smaller than the diameter of a strand of hair. These tubes are standing on end, much like a patch of grass. This arrangement traps light in the tiny gaps between the "blades” with the help of the carbon.

Ajayan said the material could be used in solar energy conversion.

"You could think of a material that basically collects all the light that falls into it," he said. It could be used in infrared detection or astronomical observation among other possible uses.

Posted by Rebecca Sato.

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Links:
http://www.reuters.com/article/scienceNews/idUSN1555030620080116?sp=true
http://www.chron.com/disp/story.mpl/front/5451632.html