nanotechnology. A Gentle Introduction to the Next Big Idea
Publisher: Prentice Hall | Pages: 208 | 2002-11-08 | ISBN 0131014005 | PDF | 1 MB
Quantum Dots contain only a few hundred atoms. Because the electrons in a quantum dot are confined to widely separated energy levels, the dot emits only one wavelength of light when excited. The size of the dot determines its electronic, magnetic, and optical properties. Quantum Dot Corporation has developed a QD cadmium selenide nanoparticle for use as biological labels. Researchers can tag proteins and nucleic acids with QD and illuminate them with ultraviolet light and the crystal will fluoresce at a specific wavelength and show the location of attached proteins. How does a QD work? An organic dye molecule absorbs only photons of light with just the right energy to lift its electrons from their quiescent state to one of the higher levels available to them. The incident light must be exactly the right wavelength or color. The molecule will emit a photon when the electron falls to a lower energy level.
