Moiré induced organization of size-selected Pt clusters soft landed on epitaxial graphene.

Two-dimensional hexagonal arrays of Pt nanoparticles (1.5 nm diameter) have been obtained by deposition of preformed and size selected Pt nanoparticles on graphene. This original self-organization is induced, at room temperature, by the 2D periodic undulation (the moiré pattern) of graphene epitaxially grown on the Ir(111) surface.

Strains induced by point defects in graphene on a metal.

Strains strongly affect the properties of low-dimensional materials, such as graphene. By combining in situ, in operando, reflection high-energy electron diffraction experiments with first-principles calculations, we show that large strains, above 2%, are present in graphene during its growth by chemical vapor deposition on Ir(111) and when it is subjected to oxygen etching and ion bombardment. Our results unravel the microscopic relationship between point defects and strains in epitaxial graphene and suggest new avenues for graphene nanostructuring and engineering its properties through introduction of defects and intercalation of atoms and molecules between graphene and its metal substrate.

Collective molecular reorientation of a calamitic liquid crystal (12CB) confined in alumina nanochannels.

We study the smectic director structure of the rodlike liquid crystal 4-n-dodecyl-4'-cyanobiphenyl (12CB) confined in cylindrical cavities of 200 nm diameter in porous alumina templates by means of combined broadband dielectric spectroscopy, optical birefringence, and neutron scattering measurements. We show that the collective molecular orientation differs between entering the smectic A phase upon cooling from the isotropic state and entering the same phase upon heating while melting the confined crystal. We discuss this collective molecular realignment in terms of a competition between weak planar anchoring at the p-Al2O3/12CB interface and a preferred texture typical of the crystallization of rodlike molecules in nanochannels (Bridgman growth).