Scientists have created the darkest material known: a carpet made of carbon nanotubes standing on end. This nanoforest can return less than 0.1 percent of the light that falls on it—a reflectance of less than one-third that of the previous record holder, a film of nickel-phosphorus alloy. (Normal black paint reflects back 5 to 10 percent.) The gaps between the nanotubes help to entrap light, and the nanotubes, grown on iron nanodots on top of a silicon wafer, are meshed together. The meshing forms an irregular surface that scatters light and thus both minimizes reflection and maximizes absorption, explain researchers at the Rensselaer Polytechnic Institute and Rice University. They suggest that the new material could boost the effectiveness of solar power cells, infrared sensors and astronomical detectors that soak up radiation from space. Absorb more in the February Nano Letters.
This article was originally published with the title "The New Black" in Scientific American 298, 4, 36 (April 2008)