Interaction between gold and sulfur in Au-nanoparticles capped with tiols: effect of particle size

RAMALLO-LÓPEZ, J. M.; GIOVANETTI, L.; REQUEJO, F. G.; ISAACS, S. R.; SHON, Y. S.; SALMERON, M.

Campinas, Brasil

Workshop; XVI Reunión Anual de Usuarios, Laboratorio Nacional de Luz Síncrotron; 2006

The interaction of gold and sulfur atoms on the surface of hexanethiol-capped goldnanoparticles was studied using X-ray absorption spectroscopy at the sulfur K andAu L3 edges. Both, EXAFS at the L3 Au-edge results and XANES at the sulfurK-edge results show a change in the S-Au interaction as function of the particlesize. These changes are attributed either to a higher sulfur coverage on the surfaceof the nanoparticle than that expected for an Au(111) surface or to geometricale®ects caused by the changes in the morphology of the nanoparticles surface withthe size. Such effects can be the variation in the tilt of the hexanethiols chainsand/or the high radius of curvature of the substrate which results in a decrease inthe chain density moving away from the surface of the core.