Synthesis and characterization of long gold nanorods

A new approach to fabricate long gold nanorods by controlling the volume of the growth solution is reported. Shapes ranging from fusiform nanoparticles to ID rods were observed to evolve. Increasing the growth solution can control the length of the nanorods. The length of the rods could be extended to 2 μm, and nanorods with aspect ratios of up to ∼70 could be obtained. Moreover, X-ray absorption spectroscopy (XAS) was used to elucidate the growth mechanism of gold nanorods. The gold ions were directly reduced to gold atoms by ascorbic acid during the reaction, and the gold atoms were deposited on the surface of gold seeds, which were introduced into the reaction. Extended X-ray absorption fine structure (EXAFS) confirmed the growth of gold and the environment around Au atoms during the reaction. XAS is expected to have wide applications in the growth of gold and other related materials.