Making the Blackest of Black Materials
Little Light Traps "We made carbon nanotubes that are blacker than anything else." 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...