Nanoparticles are tiny — the head of a pin contains about a million of 'em. Folks in the Chemistry Department of the University of California found that a solution of plastic-coated iron-oxide nanoparticles, when exposed to light from a photonic crystal, will self-assemble into three-dimensionally ordered crystals. That enables them to change the wavelength of light reflection, producing colors that vary according to the strength of the magnetic field.
The discovery was made by Yadong Yin, assistant professor of chemistry; Jianping Ge, postdoctoral researcher; and Yongxing Hu, first-year graduate student. UC-Riverside has filed a patent application.
