The characterization of asymmetric alumina membranes by Rutherford backscattering spectrometry

Effective membrane structures often rely on the presence of thin discriminating layers that exert selectivity control while maintaining high fluxes. Characterizing these separating layers is often difficult given the scarcity of analytical tools capable of measuring structural detail below sample surfaces. We have shown that Rutherford backscattering spectrometry (RBS) is an effective tool for characterizing asymmetric inorganic membranes. The ability to accurately measure the thickness and composition of thin metal layers using RBS offered a means of analyzing composite structures in which metals are deposited to influence separation or provide strength to the membrane. This analysis of commercially available alumina membranes by RBS quantified the interpenetration depth of deposited gold layers. RBS has also been applied to the measurement of sample porosity in Al2O3 membranes using specialized 16O resonance experiments. The measured porosity of these asymmetric membranes resulting from the resonance measurements was compared to a graphical analysis of scanning electron microscopy images. The results of this study suggest that RBS may offer advantages in a wide range of membrane materials analysis applications.