Patterns & pathways in nanostructure self-assembly

A nanocluster or nanocrystal is a fragment of solid comprising somewhere between a few atoms to a few tens of thousands of atoms. Nanoclusters are therefore a novel state of matter with properties that are neither those of a bulk crystal nor those of individual atoms and molecules.

Over the past 10 years huge advances have been made both in the synthesis of size-tunable, monodisperse (i.e. size-selected) nanoclusters of various chemical compositions and in the development of techniques for their assembly into nanostructured solids (facilitating the synthesis of what have been termed "designer materials"). Reference [1] provides a review of recent nanocluster science.

Pattern Formation in Nature

The self-assembly of arrays of colloidal nanocrystals produces not only close packed networks but a fascinating array of patterns that bear close similarities to those arising from a number of – at first, apparently unrelated - far from equilibrium processes. These processes include hydrodynamic flow and phase separation in binary systems.

A particularly important member of the family of patterns we observe is the cellular network. Random cellular networks are ubiquitous in nature [2]. From the microstructure of biological tissues to the distribution of galaxies in the local Universe, similar cellular characteristics are observed in systems spanning a remarkably wide range of length scales, despite their inherent disorder.

Spin coating Au nanoparticles onto Si produces nanostructured cellular networks (as shown in Fig. 1 and discussed in Refs. 3 and 4). The morphologies of these cellular nanoparticle arrays can be remarkably similar to those of other nanoscale films (including dendrimer and polymer layers).

Key aspects of our current work in this area include: