Structural Order in Ultrathin Films of the Monolayer Protected Clusters Based Upon 4-nm Gold Nanocrystals: An Experimental and Theoretical Study

NABRAJ BHATTARAI; SUBARNA KHANAL; DANIEL BAHENA; JIMENA A. OLMOS ASAR; ARTURO PONCE; ROBERT L. WHETTEN; MARCELO M MARISCAL; MIGUEL JOSE YACAMAN

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2014 vol. 16 p. 18098 - 18098

he structural order in ultrathin films of monolayer protected clusters (MPCs) is important in a number of application areas but can be difficult to demonstrate by conventional methods, particularly when the metallic core dimension, d, is in the intermediate size-range, 1.5 o d o 5.0 nm. here, improved techniques for the synthesis of monodisperse thiolate-protected gold nanoparticles have made possible the production of dodecane-thiolate saturated B4 0.5 nm Au clusters with single-crystal core structure and morphology. An ultrathin ordered film or superlattice of these nanocrystal-core MPCs is prepared and investigated using aberration corrected scanning/transmission electron microscopy (STEM)which allowed imaging of long-range hexagonally ordered superlattices of the nanocrystals, separated by the thiolate groups. The lattice constants determined by direct imaging are in good agreement withthose determined by small-angle electron diffraction. The STEM image revealed the c