ENERGETICALLY AND STERICALLY FAVORABLE ASSEMBLY OF IDENTICAL GOLD NANORODS WITH VARYING CONCENTRATIONS OF NANOSPHERES

Gold nanorod ribbon-like arrays as well as shape-separation effect of rods from sphere-like nanoparticles have been evaluated for identical nanorod suspension with various concentration of nanospheres. These sphere-rod mixtures are prepared with help of different amounts of AgNO3. Deposits of nanoparticles at various positions of the coffee-stain ring are observed in different arrangements. For instance, face-to-face aligned nanorods get settled in ribbon-like superstructures and these arrays are observed to be self-separated from spheres. Self-assembly and shape-separation effect are observed more systematic at the outer-edges than the inner-region of the coffee-stain ring. Experimentally, it has been observed that face-to-face formation of nanorods in suspension is energetically more probable arrangement. As the separation between two nanorods increases, the depth of potential well decreases, indicating that the upper layers of nanorods are more under the influence of lower placed nanorods than those placed in the same plane. Energetically and sterically, more feasible arrangements are observed.