Most of these X-ray focusing devices are well-suited for moderate X-ray energies, but for higher X-ray energies (>30 keV), they lose efficiency because the refractive index decrement, δ = 1−n ~ 10 −6, is small and scales as 1/E 2, where E is the X-ray energy. These optics all have specific advantages and disadvantages depending on the experiment and employed X-ray energy. However, there are today several types of optics for X-ray focusing utilizing different techniques including Kirkpatrick–Baez (K–B) mirrors 3, 4, 5, capillary optics 6, compound refractive lenses 7, Fresnel zone plates 8 and multilayer mirror optics 9. As the refractive index of most materials is close to unity in the X-ray range, focusing X-rays is challenging. X-ray microfocusing techniques for probing small sample volumes are important for a broad range of synchrotron radiation applications 1, 2. The coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression and relaxation behavior of samples in the DAC can be investigated with this technique. A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81 keV. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors.
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