Making the Blackest of Black Materials

"We made carbon nanotubes that are blacker than anything else."

By NASA Goddard Staff, as told to Flora Lichtman Posted 01.26.2012 at 11:20 am 10 Comments

Little Light Traps

Our material absorbs more than 99 percent of visible and ultraviolet light and 98 percent of infrared light. It’s at least 10 times as good at capturing light as black paint, so we can use it in telescopes, where stray light can contaminate measurements. The nanotubes are sparse enough that light passes between them, like sunlight through trees in a forest. When photons hit the sides of the carbon tubes, they transfer their energy to the carbon’s electrons, which start to move. The light is converted to motion—heat— which dissipates in the tube. —John Hagopian, optical physicist at NASA’s Goddard Space Flight Center

To grow carbon nanotubes, we use a substrate, an adhesion layer and a catalyst: iron. The catalyst condenses on the substrate, a lot like if you boiled water and leaned over the pot with your glasses on. Then we put the whole thing in a quartz tube furnace at 1,382°F. We introduce ethylene gas, which is where the carbon comes from. The catalyst reacts with the gas, and the carbon molecules dissociate and form a tubular hexagonal lattice—a nanotube—on the surface of the iron. The nanotubes can grow in less than a minute. —Stephanie Getty, technologist, NASA Goddard

We put the nanotubes in an integrating sphere—a globe with a highly reflective coating inside. We shine light at the sample and, using a detector, measure the amount of light that bounces off the material. We put a shader near the detector to make sure it’s not getting direct radiation and skewing the results. One thing that’s kind of amazing is that the nanotubes, which are just 100 microns tall, can absorb infrared rays, which have wavelengths the same size as the nanotubes.—Manuel Quijada, engineer, NASA Goddard

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10 Comments

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D13

01/26/12 at 11:39 am

Well, well. I guess radar absorbing materials just got whole lot cheaper. Lets see if this starts replacing expensive radar absorbing metameterials. Sounds like its pretty cheap to make too. Stealth bycicle anyone?

Or how about now lets convert 90% of that light to energy!

Great article popsci!

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."

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Eric18

01/26/12 at 12:37 pm

Ok so this isn't new right??? There has been at least two other articles about the Blackest Material that absorbs 99% of light. Although I love this allot I haven't really gotten an answer to my question. Can this be used in Solar Panels/Cells to convert visible light, ultraviolet light and infrared rays to energy greater then Solar Panels/Cells we already have????

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C--

01/26/12 at 12:39 pm

Its all nice and Shiny, BUT! There's one thing no-one seems to take note of and I quote: "The light is converted to motion—heat— which dissipates in the tube."

How can this be used for Stealth by any means If all it does is absorb and re-radiate the captured light as heat (Infrared radiation, for those who don't know)?
That way of thinking it could be used for stealth just makes no sense to me!

Now obviously using this in Telescopes to capture stray light is great! But aren't we also oppening another can of worms/problems here?
As I know, Keppler and many other new Space Telescopes are Cryogenically cooled to make them more sensitive to weak incoming photon radiation. Wouldn't this extra heat release from the absorbent material clash with the idea of the cooling system?

Great, but with slightly overlooked flaws...
Thats my oppinion about this.

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eregorn8

01/26/12 at 12:58 pm

This material is still not "black" because like every other physical object it still has blackbody radiation(like what makes a poker glow white or your stove top glow red). So unless this material is supercooled to near absolute 0 (-273C) it still isn't "black".

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emneumann

01/26/12 at 1:37 pm

@C-- space based telescopes wouldn't benefit from this in the same way terrestrial telescopes would. The tube coating on earth bound telescopes is fighting light pollution from terrestrial sources and atmosphere. Not a problem for orbital observatories where the only problem would be from off axis targets which are typically going to be very dim to begin with.

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xalar

01/26/12 at 2:27 pm

Can this technology be used to remove glare on a laptop screen from a low angle?

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derlange

01/26/12 at 4:26 pm

Did you guys see something I didn't in the article? Where does it mention that this material absorbs RADIO waves to the same degree as the UV, Visible and IR wavelengths of light? The wavelength of radio waves (used in radar) is much longer and may react differently than their IR, Vis, UV counterparts.

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jefro

01/26/12 at 10:34 pm

I suspect a better use may be to apply to materials designed to absorb heat. Such as heat to energy type of solar energy device or simple heater for water/air.

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Infinion

01/27/12 at 2:35 pm

it'd be a great material for use in a solar furnace to achieve higher temperatures, but how much would this material cost?

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D13

01/30/12 at 11:30 am

Is the argument can this material be applied to something that counteracts the effects of heat? Thats not an argument or a reason why this isn't amazing.

They already have liquid cooled skins on stealth airplanes. The wings have pores in them. Air friction has always been a big heat generator. This problem can be delt with in a number of ways. Did you think the radar absorbing material on stealth aircraft didnt run into the same problems? They have extrememly small heat signatures (if any) for a reason. Yes they have the engines usually partially shielded but they have air-friction and heat from the sun hitting them at any given moment during the day...they still dont leave heat signatures from their wings and body (for the most part). Stealth aircraft are no joke and I can guarantee you that this material (or a version of it) will replace the expensive materials used on those aircraft soon. Also, think of underwater applications...invisible mines would be very very nasty. How many you think are already in development? You can go with a much simpler technology on the inside as long as its hidden. Blackbox radiation/heat not a blocking issue with this breakthrough.

I would say that since the layers need only be so thin, that the radiation will most likely start at the bottom of the material. You could use a magnetic field to help direct that radiation in any case. This may be one of those techs that is just now becoming discovered by mainstream but has been around a while?

"Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. There is no spoon."