Goldie Oza, Sunil Pandey, Ritu Shah, Mayuresh Vishwanathan, Rohan Kesarkar, Maheshwar Sharon and Madhuri Sharon
We report synthesis strategies developed to achieve decent yield of monodispersed gold nano rods (GNR) of desired aspect ratio. The color and optical properties of gold nano particles originate from localized surface plasmons. Unlike nano-sphere the optical properties of GNR are influenced by their shape anisotropy. UV-visible absorption spectroscopic measurements and Scanning as well as Transmission electron microscopy (SEM and TEM) images provide an explanation for formation and mechanism for controlling the GNR growth. The work emphasizes on the standardization of parameters like concentration of aurochloric acid, cationic surfactant CTAB (hexadecyltrimethylammonium bromide) and silver nitrate; as well as pH and Temperature of reactant and finally efforts to separate GNR by centrifugation. Use of CTAB at 0.2M concentration and 200 C and a ratio of 200:1 of CTAB and gold salt, resulted into formation of metallo-micellar complexes. This complex acted as seed and resulted in formation of 1D crystal growth of nanorod. The most decisive parameter affecting the nucleation was found to be concentration of gold ions (1mM). Growth of GNR was mainly controlled by AgNO3 (4mM) and CTAB (0.2M). Centrifugation was found to help the shape separation i.e. separating GNR from other shapes of gold nanoparticles.. A blend of theoretical as well as experimental discussion is made to comprehend the idea behind separation of the GNR from the mixture of spheres and rods
