Synthesis of Gold nanoparticles and characterization by Dynamic Light Scattering (DLS) technique Group 3
Dynamic light scattering (DLS), also referred to as photon correlation spectroscopy or quasi-elastic light scattering, is a procedure used commonly for characterizing particle size and size distribution of nanoparticles in suspension or polymers in solutions. This technique is based on the Brownian motion of spherical particles which causes a Doppler shift when the light hits the moving particle of incident laser light2. The Brownian motion is the random movement of particles due to the bombardment by the solvent molecules that surround them. The translation diffusion coefficient (D) of particles is measured and the size of the particles is calculated according to the Stokes−Einstein equation.1 DLS is used routinely to analyze the size and size distribution of proteins, polymers, nanoparticles and colloids. By evaluating the variation of the scattered light intensity as a function of time, the hydrodynamic size of particles and particle agglomerates can be determined. Because of the strong light scattering property of gold nanoparticles, it is expected to assume that DLS can be a very trustworthy technique for quantitative detection 1. Experimental Procedure
Our objective in the lab was to synthesize gold nanoparticles using a bottom up chemical method. In the lab we attempted to synthesize two sets of gold nanospheres both 50nm in diameter. We began this lab experiment by preparing a solution of gold chloride and deionized water. This solution was set aside while another solution consisting of ascorbic acid and deionized water was mixed. Care was taken to protect this solution from light because the ascorbic acid is light sensitive. This solution was also set aside for use later in the lab. The third solution we prepared was that of deionized water and trisodium...
References: 1. Berne, B. J.; Pecora, R. Dynamic ligh scattering: with applications to chemistry, biology, and physics; Wiley: New York, 1976.
2. Malvern DLS technical note
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