Providing the "missing link" between atomic and nanoparticle behavior in noble metals, these multi-electron "artificial atoms" could also serve as light-emitting sources in nanoscale optoelectronics and in energy transfer pairs.

"We have discovered a new class of quantum dots that are water soluble, strongly fluorescent, and display discrete excitation and emission spectra that make them potentially very useful for biological labeling," said Robert Dickson, associate professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology. "Their potential applications are really complementary to those of semiconductor quantum dots."

The gold nanodots are made up of 5, 8, 13, 23 or 31 atoms, each size fluorescing at a different wavelength to produce ultraviolet, blue, green, red and infrared emissions, respectively. The fluorescence energy varies according to the radius of the quantum dot, with the smallest structures the most efficient at light emission.

In contrast, quantum dots made from semiconductors such as cadmium selenide are much larger, containing hundreds or thousands of atoms. Semiconductor quantum dots obey different size scaling under confinement, producing weaker emissions.

The gold quantum dots were reported August 13 in the journal Physical Review Letters, and highlighted on the journal cover. Additional information on the work will be presented August 23rd at the 228th national meeting of the American Chemical Society in Philadelphia, PA. The work was sponsored by the National Science Foundation, National Institutes of Health, Sloan and Dreyfus Foundations, Blanchard and Vassar Woolley Endowments and the Georgia Tec
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Contact: John Toon
john.toon@edi.gatech.edu
404-894-6986
Georgia Institute of Technology Research News
23-Aug-2004