Tuning the electronic behavior of Au nanoparticles with capping molecules

The electronic behavior of gold nanoparticles (NPs) of similar to2 nm capped with dendrimer and thiol molecules was studied with Au L-3,L-2-edge x-ray absorption near-edge structure (XANES). The results reveal the tunability of the d-electron distribution in the Au NPs by selective capping. That is, that the Au atoms in the NPs gain 5d electrons (relative to the bulk) when capped with weakly interacting dendrimers and lose 5d electrons when capped with strongly interacting thiol molecules. A semiquantitative analysis of the d-charge (holes) distribution is presented. This work demonstrates the important role of the capping molecules in the d-charge distribution of Au NPs and the usefulness of XANES in probing the electronic behavior of transition metal NPs. (C) 2002 American Institute of Physics.