Self-assembling of gold nanoparticles in one, two, and three dimensions

In the present work, we report the growth of ordered arrays of gold nanopar ticles passivated with n-alkylthiol molecules using crystallization in tolu ene vapor. We kept constant the average particle size and the length of the passivating molecule (1-dodecanethiol). The temperature and time of growth were varied. We show that in the initial stages of the growth, nano-chains of particles are produced. These nano-chains aggregate to form two-dimensi onal arrays. In the initial stages the nano-chains form a two-dimensional s quare lattice which then relaxes to a close-packed structure. In latter sta ges of growth a three-dimensional supercrystal is produced. It is found tha t the packing of nanoparticles corresponds to an average FCC lattice. Howev er, large variations on the local parameters of the lattice are observed, N ear the edges of the supercrystal the anomalous packing reported by Zanchet et al. [20] and Fink et al. [21] was observed. The energy of the observed structures is analyzed using molecular dynamics simulation. It is concluded that using the vapor growth method, it is possible to produce controlled o rdered structures from one to three dimensions.