Nanowires, scanning electron micrograph (SEM). This image shows four rows of nanowires and their corresponding nanowalls, nicknamed 'nano LEDs' because they emit light when electrically charged. The distance across the micrograph is approximately the diameter of a human hair. This research was carried out at the Chemical Science and Technology Laboratory (CSTL) of the National Institute of Standards and Technology (NIST). Image published in 2010.