Local structure of Ag/Au core/shell nano-particles studied by XAFS

Abstract

We have measured Ag K- and Au LIII-edge EXAFS (extended x-ray absorption fine structure) for Ag/Au core/shell particles. The structural parameters were obtained from EXAFS curve-fitting analyses and were discussed in comparison to the structure estimated from TEM (transmission electron microscope) analyses. The thickness of the shell and diameter of the core can be evaluated from EXAFS that are fairly consistent with the results estimated from TEM. From EXAFS two-shell model analyses the Ag-Ag distance decreases and Au-Au distance increases in the thinner shell. This result suggests that the electrons transfer from Ag atom to Au atom at the interface between core and shell atom. © 2006 The Surface Science Society of Japan.