High-resolution monochromator using a high-efficiency single-mode x-ray resonator at Laue incidence.

We report a high-resolution and high-efficiency monochromator with energy resolution, ΔE/E∼2.08*10-7, utilizing a hard x-ray single-mode Fabry-Perot (FP) resonator at Laue incidence at 14.4388 keV. Instead of using multiple-crystal diffraction via several asymmetric-cut crystals, a 3 meV single-peak is generated from the interference of a Si-made two-plate cavity with a thickness of 70 µm and a gap of 45 µm, where a (0-40) Laue reflection is used to excite the backreflection (12 4 0) for the enhancement of the FP efficiency. Due to the large angular acceptance of (12 4 0) and (0-40), the energy tunability can be achieved by changing the incident angle into the resonator. The application of x-ray resonators at Laue incidence as a monochromator can be further implemented to x-ray optics.

Revisiting La0.5Sr1.5MnO4 lattice distortion and charge ordering with multi-beam resonant diffraction.

Sinusoidal wave type distortions of La0.5Sr1.5MnO4 in the low-temperature orthorhombic phase were observed using multi-beam resonant X-ray diffraction (MRXD) with (7/4 7/4 0) fractional primary diffraction. Two four-beam diffractions with opposite asymmetry were measured at 6.5545 keV and compared with the curves simulated by the dynamical X-ray diffraction theory. This approach provides the possibility of resolving the distortion modes which are perpendicular to the momentum transfer by a single azimuthal scan. The paper also demonstrates the sensitivity of MRXD profiles versus incident X-ray energy in the vicinity of the Mn K edge to the charge disproportion between the two manganese sites, reconfirming the small charge disproportion feature.