Construction and performance of the millisecond-to-second QXAFS platform at SSRF BL11B for in situ dynamic characterization

A dedicated quick-scanning X-ray absorption fine-structure (QXAFS) platform has been established at the SSRF BL11B beamline for in situ and operando studies of dynamic structural evolution on the millisecond-to-second timescale. The system combines a torque-motor-driven Si(111) monochromator, synchronized high-speed acquisition and automated data processing, and operates over an energy range of 5-26.5 keV. Rapid measurements were demonstrated with spectrum acquisition times down to 10 ms for narrow-range XANES, 16.7 ms for full-range EXAFS extending up to k ≃ 12.5 Å^-1, and 50 ms for fluorescence-mode XANES on dilute samples. Quantitative evaluation of frequency-dependent spectral quality further defines practical monochromator oscillation frequencies for the present BL11B platform: approximately 4 Hz for full-range EXAFS over a ∼1000 eV scan window and approximately 30 Hz for short-range XANES over a ∼130 eV scan window, with these recommendations determined by the response characteristics of the current detection system. The capability of the platform is illustrated by in situ monitoring of electrocatalyst reconstruction during the oxygen evolution reaction.