The identification and measurement of surface/subsurface elements is an important capability in materials science. Often destructive methods such as FIB-SEM are used to identify subsurface materials. X-ray techniques are attractive in that they are non-destructive. X-ray fluorescence (XRF) uses an X-ray source to illuminate a sample and a sensor to detect characteristic X-rays. However, XRF instruments available on the market are 2D in nature and there is little to no depth discrimination. A non-destructive and volumetric technique is preferred. Confocal micro X-ray fluorescence (confocal MXRF) is a 3D analytical technique used to measure the position and density of elemental constituents. This technique is useful for identifying constituents, measuring composition, and quantifying density variations in low density materials (~10 mg/cm3). Confocal MXRF uses a polycapillary optic to focus X-rays from a source onto a sample. A second optic, coupled to the detector, is used to detect X-rays which are only from the point of focus. Thus, it is possible to collect 3D MXRF data point-by-point without spectral contamination from material outside the focal volume. Previously, we demonstrated that this technique, when coupled to nano X-ray tomography, is capable of quantifying Ge dopant concentrations in one micrometer thick films present within polymer capsules. We have demonstrated this technology with an instrument initially designed to characterize radioactive materials, but have now constructed a second generation instrument designed specifically for transition metal elements. Design enhancements include: a higher wattage Mo tube; a vacuum chamber to better analyze low atomic number materials; improved coupling of the optics to the detector; higher spatial resolution; and full spectral data acquisition. Another unique capability is facilitated by a motorized detector optic, enabling rapid identification of regions-of-interest (ROIs) via 2D XRF mapping without the detector optic and automated insertion of the optic for 3D XRF imaging in the ROIs. Our focal spot size (X-ray wavelength dependent) is a spherical volume approximately 30 µm in size. Initial experiments demonstrating the capabilities of the instrument to analyze thin films along with multi-instrument measurements will highlight the non-destructive nature of this technique. Together these enhancements will reduce analysis time (&gt;4X), increase workflow, and improve the sensitivity of elemental analysis.

3D elemental identification and quantification using confocal x-ray fluorescence

251st National Meeting (2016)

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