Simple Optical Layout with a Diamond Crystal Monochromator for X-ray Spectromicroscopy

The study introduces a concept for an undulator beamline at a synchrotron radiation facility designed to combine confocal X-ray fluorescence microscopy (сonfocal μXRF) with micro-X-ray absorption near edge structure spectroscopy (μXANES). The optical layout employs a compact diamond channel-cut monochromator positioned near the focus of the undulator beam. The analysis includes an evaluation of the thermal load on the diamond monochromator and a simulation of the steady-state temperature distribution and thermally induced deformations in the crystal under water-cooling conditions. In maximum thermal load regime, the slope error of the deformed surface of the crystal’s first lamella remains significantly smaller than the angular convergence of the undulator beam, its angular size at the sample, and the rocking curve width of the crystal. The study also estimates the energy resolution of the diamond monochromator C(111), considering both the beam convergence and the temperature difference between the crystal lamellae. The results demonstrate that a diamond monochromator can operate near the focus of a high-power undulator beam at a fourth-generation synchrotron source, confirming the feasibility of the proposed beamline design.