Surface state of nanocrystalline RuO 2 -based electrocatalysts probed by soft XAFS

approach for analysis of EXAFS data. Therefore, a more complex method for modeling of (E) vs. E data had to be employed. First, we had to determine the correct atomic background functions, which would include the double-electron excitation events for Ru. To obtain precise values, we used theoretically predicted energies for Ru [5] and refined them using EXAFS data of Ru metal, which has relatively simple crystal structure. It turned out that the adequate refinement could be achieved if one takes into account three excitation energies with the refined values of 65.6, 305 and 520 eV, which correspond to 4p1/2, 3d5/2 and 3p1/2 excitations [5]. The contribution of the other excitation channels to atomic background was found to be insignificant. These refined energies were used to formulate the model for the refinement of local structure of RuO2 using TEY and AEY data. Table 1 compares the results of the local structure refinement using conventional approach [6] for bulk samples, when the data were collected at the NW-10A beam line, with the refined values for TEY and AEY data at L- absorption