Performance of nearly fixed offset asymmetric channel-cut crystals for X-ray monochromators

Abstract

A novel, asymmetrically cut, channel-cut crystal was designed and manufactured with the aim to significantly reduce the beam offset change during energy scans. The improvement was verified with synchrotron radiation from an undulator source. The importance of even small, generally so far neglected, asymmetries is pointed out for high-accuracy monochromators.

A simple method for mitigating error in the fixed-offset of a double-crystal monochromator

“…where is the angle of incidence on the first and second crystal diffraction planes, which are maintained parallel to meet the diffraction condition on both crystals, and and are the differences between and the incident angles on the second and first crystal surfaces, i.e. the miscut angles, respectively (Frahm et al, 2019). A schematic of X-ray diffraction from a DCM with asymmetric crystals is given in Fig.…”

“…which is found by substituting the right-hand side of equation (2) for g() and 2 sin cos for sinð2Þ in equation ( 8) (Frahm et al, 2019). For small and , equation (10) becomes…”

Fast Chemical Contrast by X-ray Fluorescence Intensity Ratio Detection

“…1−4 Fast scanning X-ray monochromators were developed at SR sources to measure XAS in transmission mode with frequencies up to 200 Hz to follow chemical reactions. 5,6 However, many studies require XAS detection in fluorescence mode because of low analyte concentration or the experimental conditions around the sample (e.g., in situ studies). The data acquisition rate is limited in fluorescence-detected XAS using energy-resolving solid state detectors by nonlinearity of the photon detector at high photon fluxes.…”

“…Possible applications include screening of a large number of samples, spatial mapping, and imaging or time-resolved experiments. X-ray absorption and emission spectroscopy (XAS, XES) are employed at synchrotron radiation (SR) sources, free electron lasers, and in laboratories for element-selective chemical characterization. − Fast scanning X-ray monochromators were developed at SR sources to measure XAS in transmission mode with frequencies up to 200 Hz to follow chemical reactions. , However, many studies require XAS detection in fluorescence mode because of low analyte concentration or the experimental conditions around the sample (e.g., in situ studies). The data acquisition rate is limited in fluorescence-detected XAS using energy-resolving solid state detectors by nonlinearity of the photon detector at high photon fluxes .…”