The application of shadow nanosphere lithography for the preparation of large-area, two-dimensional, metallic nanostructures of different shape is described. Through changing the mask morphology by temperature processing and varying the evaporation conditions, particles with morphologies such as rings, rods, and dots have been produced. This process allows outstanding control of the size and morphology of the particles. The efficient technique is shown to scale down the size of metallic nanoparticles from 200 to 30 nm, while preserving the original nanosphere spacing and order. The 150-nm-diameter Fe rings produced by this method show ferromagnetic behavior, which was predicted by theoretical simulation. All the experimental results were confirmed by computer simulations, which also showed the possibility of creating periodic arrays of any other geometrical shape.

In this letter we describe the preparation of large-area, two-dimensional metallic structures using shadow nanosphere lithography. By varying the position of the substrate with respect to the evaporation source during the sample preparation, we make morphologies such as cups, rods, and wires, that are not accessible by the standard nanosphere lithography. This technique also allows for an encapsulation of the metallic structures, to prevent them from oxidation. Morphologies predicted by our computer simulations have been subsequently confirmed experimentally.

Multiwall carbon nanotubes (CNTs) have been assembled on various types of colloidal templates using the well-known polyelectrolyte-assisted layer-by-layer (LBL) assembly technique. Dense mono-and multilayers of CNTs were successfully deposited on silica, polystyrene, and melamine spherical colloids of different size, showing that relatively short CNTs completely wrap the surface of the spheres, while long nanotubes stick out of the surface, allowing them to contact various spheres at the same time. Decomposition of the colloidal template leads to formation of hollow CNT spheres, which was demonstrated through treatment of melamine@CNT particles with HCl. The deposition was also carried out on ordered arrays of polystyrene particles, leading to nanostructured, conducting CNT assemblies. Rupture of the assemblies with ultrasound shows that the assembly only takes place on one-half of the colloid spheres, so that "Janus" particles with asymmetric functionalities can be easily prepared.