Size-controlled synthesis and characterization of thiol-stabilized gold nanoparticles.
Size-controlled synthesis of nanoparticles of less than a few nanometers in size is a challenge due to the spatial resolution limit of most scattering and imaging techniques used for their structural characterization. We present the self-consistent analysis of the extended x-ray absorption fine-structure (EXAFS) spectroscopy data of ligand-stabilized metal nanoclusters. Our method employs the coordination number truncation and the surface-tension models in order to measure the average diameter and analyze the structure of the nanoparticles. EXAFS analysis was performed on the two series of dodecanethiol-stabilized gold nanoparticles prepared by one-phase and two-phase syntheses where the only control parameter was the gold/thiol ratio xi, varied between 6:1 and 1:6. The two-phase synthesis resulted in the smaller particles whose size decreased monotonically and stabilized at 16 A when xi was lowered below 1:1. This behavior is consistent with the theoretically predicted thermodynamic limit obtained previously in the framework of the spherical drop model of Au nanoparticles.
Frenkel
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Physics Department, Stern College for Women, Yeshiva University, New York, New York 10016, USA. anatoly.frenkel@yu.edu
Nemzer
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Pister
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Soussan
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Harris
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Sun
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Rafailovich
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