| Abstract
| - Several kinds of organization were observed on self-assembled mono- and bilayers of 4-nm-sized ruthenium particles coated with alkanethiol: lines of edgewise stacked platelets; hexagonal network; and both compact and noncompact stacking of hexagonal arrays into bilayers. In the noncompact stacking, moiré images resulted from the twisting of the two layers. The originality of these patterns can be related in some extent with the hcp structure of the ruthenium particles.
- Ruthenium nanoparticles were prepared by reduction of RuCl3 in a liquid polyol. The meanparticle size was restricted to the 1−6 nm range by appropriate choice of the reductiontemperature and the acetate ion concentration in the solution. Very narrow particle diameterdistributions were obtained. In some samples, among nearly isotropic particles, plateletswith aspect ratios as low as 1/4 were detected. Colloidal solutions in toluene were obtainedby coating the metal particles with dodecane thiol. Self-assemblies of 4-nm-sized coatedparticles were studied on a transmission electron microscope grid. The dodecane thiolconcentration in the colloidal solution was found to determine, within the particle monolayer,the formation of either columnar units made up of edgewise stacked platelets, or a hexagonalnetwork with a mean distance between the particles of 2 nm. The stacking of hexagonalarrays of particles was also studied, and both closed-packed and noncompact stackings werefound. In the noncompact stacking, moiré images resulted from the twisting of the twohexagonal layers with respect to each other. Reconstructions of moiré patterns were observedto favor the 6-fold and 2-fold sites.
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