Variable sample exit angle x-ray fluorescence spectroscopy (VEA-XRF) employing the Lβ/Lα intensity ratio for transition metals and their oxides has been shown to be useful for non-destructively studying transition metal surfaces and oxidation, as well as, superconductors. Thus the theoretical formulation of the Lβ/Lα intensity ratio dependence on the sample exit angle, θe, is of some interest and we develop it here. We also present methods of obtaining parameters needed in the formulation, such as Lβ absorption coefficients, which are not available in the literature, for wavelengths greater than about 12Å.
Recently variable sample exit-angle x-ray fluorescence spectrometry (VEA-XRF) has been shorn to be a useful analytical tool for monitoring the oxidation of the surfaces of bulk Cu, Ni as well as that of Fe. In these studies advantage was taken of the well known phenomenon that for each transition metal oxide (MO) Lβ/Lα intensity ratio value is higher than for the transition metal (M), itself. Within the limits of the photon-escape depth de, which for these photons are generally below 5000 Å, varying the sample exit-angle θ offers an opportunity for seeing whether or not the oxidation of the surfaces of bulk M belongs to one of the following two classes: (I) uniform oxidation throughout the entire observable sample-depth, (II) preferential oxidation of the top surface layer, i.e. depth dependent oxidation.
Characterization of Metal Doped Polymer Capsules using Confocal Micro X-ray Fluorescence Spectroscopy and X-ray Computed Tomography