  In-situ EXAFS experiments were performed at the Ag $K$-edge after adsorbing
NO on the hydrogen reduced silver cluster. The coordination parameters, i.e.
inter-atomic distance, coordination number and Debye-Waller factor were derived
from a three-shell fitting model including a split Ag-Ag shell and a single
Ag-O(N) shell. The multiple-shell fitting proved that the reduced silver
cluster underwent a slight change in the local structure. After co-adsorbing NO
and oxygen, the difference file fitting technique was used for isolating each
of the first Ag-Ag(1) and Ag-O(N) shell contributions to the EXAFS spectra
filtered in R-space of Fourier transform.
