Schematic layout of the used geometry and explanations for the symbols used in the text. The Rowland circle is defined by the sample and detector positions and the curvature radius of the analyzer. The analyzer can be moved with respect to the circle by the distance if additional opening of the bandwidth according to Eq. (4) is desired, but the detector and the sample should not be moved with respect to each other.
(Color online) The focal image of a diced analyzer crystal in the considered geometry as predicted by a ray-tracing simulation. Different colors represent different photon energies; the total energy gradient is in this case observed to be .
(Color online) The focal image of a diced analyzer crystal in the present geometry as measured with a pixel detector.
(Color online) The projections of the focal image presented in Fig. 3 in both dispersive (top) and nondispersive (bottom) directions.
(Color online) Resolution of the spectrometer with high-resolution setup with Si(553) channel cut. Top: measured at a fixed incident energy of and recording the image on the detector. Bottom: measured by tuning the incident photon energy and keeping the analyzer Bragg angle fixed.
(Color online) Top: Image recorded on the detector showing the quasielastic line and RIXS signal from a sample of . Bottom: Corresponding spectrum obtained by summing over the pixels in the nondispersive direction. The data were recorded with a resolution of FWHM.
Contributions to the final resolution function of the present experiment. When the finite incident bandwidth is deconvoluted from the measured resolution function, the resolution of the spectrometer itself is found to be at an incident photon energy of . The calculation assumes a Gaussian shape for all components.
Examples of energies of absorption edges for certain elements. Typically usable analyzers with the corresponding Bragg angles are listed together with the reflection Darwin widths (DWs) and the pixel-size effects (PSEs) for a typical detector with pixel size. The PSE is calculated based on a Rowland circle geometry. Total expected resolutions are from the convolution of the Darwin width and the PSE, assuming Gaussian components.
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