| Nanoparticle-solvent films deposited on solid substrates are associated with a rich dynamic behaviour which gives rise to a wide variety of striking self-organised patterns. We have used a combination of optical microscopy, atomic force microscopy, and Monte Carlo simulations to study the self-organisation of Au nanoparticle arrays from organic solvents on silicon substrates. Simple drop deposition methods have been complemented with -Y´meniscus-driven assemblyˇ experiments which allow fine control over solvent evaporation and dewetting. Fingering patterns reminiscent of those seen in polymer and water thin films are observed at both the macroscopic level (at the dewetting front) and at the microscopic scale. Real-time monitoring by optical video-microscopy of nanoparticle deposition was carried out using a novel contrast enhancement technique [see www.nano-lane.com], providing key insights into the self-organisation of the particles at the substrate-solvent interface. A modified version of the Monte Carlo algorithm first put forward by Rabani et al. [E. Rabani et al., Nature 426, 271-274 (2003)], incorporating a disjoining pressure term in the Hamiltonian [Martin et al., Phys. Rev. Lett., at press (2007)], reproduces our experimental observations well. |
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