They are human-made nanoparticles so small that their properties are governed by quantum mechanics. Those properties include the emission of light: The wavelength of light they emit depends solely on the size of the particles. Electrons in larger particles have less energy and emit red light, whereas electrons in smaller particles have more energy and emit blue light.<\/p>\n

Researchers can precisely determine what color of light will emerge from the quantum dots simply by regulating their size. That offers a huge advantage over the use of other kinds of fluorescent molecules, for which a new type of molecule is needed for every distinct color.<\/p>\n

This advantage in controllability isn\u2019t limited to the color of quantum dots. By adjusting the size of the nanoparticles, researchers can also adjust their electrical, optical and magnetic effects, as well as physical properties like their melting point or how they influence chemical reactions.<\/p>\n