The Preparation of Gold Nanoparticles

2003 Summer Research Students: Alison Williams ('04) and Chorthip Peeraphatdit ('05)

2004 Summer Research Student: Melanie Ufkin ('06)

The preparation of gold (Au) nanoparticles by reducing Au(III) using sodium citrate is an inexpensive and straightforward procedure that requires about 30 minutes to complete. This reaction yields a deep red solution containing 10-20 nm diameter Au nanoparticles with a characteristic absorption peak at ~ 520 nm. This absorption is very sensitive to the interparticle distance. Students can characterize the color of the solution using the Ocean Optics visible spectrometers, and correlate the position of the absorption peak with both the size of the nanoparticles and the interparticle distance. Making the interparticle distance much smaller, e.g. by replacing the citrate ions with chloride ions, dramatically changes the appearance of the solution from red to deep blue/purple.

Links: http://mrsec.wisc.edu/edetc/cineplex/gold/index.html

Collaborators: George Lisensky, Department of Chemistry, Beloit College

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Last updated June , 2005

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