The electronic and geometric structure of the Pd/Ag-H system, an important hydrogen membrane structure, has been studied with x-ray absorption spectroscopy. Palladium L 3 XANES measurements in both vacuum and in situ under hydrogen atmosphere were performed at room temperature on an ideally mixed Pd 0.8 Ag 0.2 system obtained with bi-sputtering, and on a pure Pd system obtained with electroless plating. A model of fcc-Pd/Ag with the Ag atoms evenly distributed through the system and the hydrogen atoms placed in the octahedral holes was able to explain the observed XANES in great detail. FEFF calculations show that the Pd/Ag-H system generates an anti-bonding Pd-H band, in close agreement with the experimental results. In addition the calculations show that the hydrogen content of the system strongly influences the XANES, especially the intensity of the white-line and the anti-bonding peak. In contrast the influence of the Ag atoms is limited to relatively small changes in the white-line intensity. However change of the Ag distribution within the Pd/Ag fcc lattice from well-mixed to clustered was found to have a significant influence on the Pd L 3 edge white-line intensity.

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Rutherford backscattering (RBS) was used to determine the thickness and composition of several micrometers thick electroless-plated Pd/Ag alloy layers deposited on porous ␣-alumina. To determine the composition of the alloy, the thickness of the Pd layer after the first synthesis step and the thickness of the Pd/Ag sandwich structure after the second synthesis step were determined. The error in the determined thicknesses (±5%) is much smaller than for the commonly used techniques, i.e., the weight difference and the scanning electron microscopy (SEM) cross-section method. RBS allows accurate determination of plating rates and an even more accurate value for the composition, since the error in the thickness is mainly systematic. This enables one to tune the synthesis parameters for layer thickness and alloy composition.A further and very important advantage of RBS is that pore filling of the support can be studied. Results showed that Pd penetrates into the alumina support during plating, with RBS it could be detected up to 1.4 m deep. It is estimated that the equivalent of 0.1 m bulk Pd is present in the pores of the support of typical electroless-plated samples.