IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Molecular conformation changes in alkylthiols ligands as a function of size in gold nanoparticles
Autor/es:
RAMALLO-LÓPEZ, J. M.; GIOVANETTI, L. J.; REQUEJO, F. G.; ISAACS, S. R.; SHON, Y. S.; SALMERÓN, M.
Lugar:
Universidad de Stanford, Stanford, USA
Reunión:
Conferencia; 13th International Conference on X-ray Absorption Fine Structure; 2006
Resumen:
The bonding of
hexanethiols to gold nanoparticles of 1.5, 2.0 and 3 nm was studied using X-ray
Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine
Structure (EXAFS). The XANES spectra revealed that a substantial fraction of
weakly bound hexanethiol molecules are present in addition to those forming
covalent bonds with Au atoms. The weakly bound molecules can be removed by
washing in dichloromethane. After removal of the weakly bound molecules the S
K-edge XANES reveals peaks due to S-Au and S-C bonds with intensities that
change as a function of particle size. Au L3-edge EXAFS results indicate that
these changes follow the changes in coordination number of Au to the S atoms at
the surface of the particles. This higher accessibility for S atoms to bond
gold atoms can be explained by the high curvature of small NP.