Blasts of laser light lasting a few millionth billionths of a second can turn the polished surface of any metal ultra-black, by covering it with nanoscale ridges and crevices. US researchers say the trick could one day be used to make better solar panels and more efficient fuel cells.
Chunlei Guo and colleagues at Rochester University in New York, US, used a titanium-sapphire laser, which requires only a normal power supply, to repeatedly blast samples of polished metal with pulses lasting 65 femtoseconds each.
After just a few pulses, "we found femtosecond pulses can reshape the metal's surface into a range of different nanostructures," says Guo. The resulting nanoscale pattern of cavities and protuberances traps light so efficiently that a shiny surface turns jet black.
"The new surface can absorb very close to 100% of light," says Guo. The technique was also found to work on copper, gold, platinum, aluminum, titanium, zinc and tungsten.
Source:
http://www.newscientisttech.com/article/dn10647-ultrashort-laser-pulses-turn-metals-pitch-black.html
