Microsecond X-ray reflectometry measurements of an Au (300 A) | Cr (80 A) | Si sample

Dataset for the publicationM. Haberl, M. Eder, E. Pfeiler, D. Schumi-Mareček, F. Bertram, P. Mikulı́k and S. Kowarik (2026). J. Appl. Cryst. 59, https://doi.org/10.1107/S1600576726004449. Datasets of an Au (300 A) | Cr (80 A) | Si sample as proof-of-concept for a fast XRR method that enables net scan times in the upper microsecond range.Measurements were performed at DESY Petra III, beamline P08 in collimation mode at 18 keV.The sample was fixed on a galvanometer scanner and oscillated at frequencies between 50 Hz to 1900 Hz.The detector (DECTRIS Eiger2 X 1M) used a framerate between 100 to 3800 frames/second for up to 3800 XRR curves per second. Dataset includes the following scans:scan-id:734 9.95 ms exposure time per scan (100 scans)739 2.45 ms exposure time per scan (100 scans)745 950 μs exposure time per scan (100 scans)747 950 μs exposure time per scan (100 scans)799 450 ms exposure time per scan (100 scans)835 213 μs exposure time per scan (100 scans) 888 Pilatus888_conventional XRR scan (1 s/point) as reference calibration scans, only in raw.zip733 20 s exposure at 50 Hz (triangle) for movement calibration738 20 s exposure at 200 Hz (triangle) for movement calibration744 20 s exposure at 500 Hz (triange) for movement calibration746 20 s exposure at 500 Hz (sine) for movement calibration794 20 s exposure at 1000 Hz (sine) for movement calibration833 20 s exposure at 1900 Hz (sine) for movement calibration 509 conventional XRR scan (1 s/point) without detector slits for detector calibration (Pilatus 100k)967 Silver Behenate XRD pattern for detector calibration (Eiger2 X 1M) Fast_XRR_audacity.zip contains readout from the sensor of the galvanometer for exposure time correction The reduced data is given as .ort and .h5 files following the ORSO standard.Data reduction includes background subtraction, attenuation correction, footprint and exposure time correction and intensity normalization.Apart from q, R, R_err (sigma) and q_err (FWHM), additinal columns (raw counts, average background, normalization factor, attenuation factor, effective footprint and exposure time) are provided.These are used for Poisson log-likelihood fitting and least-squares fitting with the Anscombe transformation, which is necessary for the 213 μs and 450 μs exposure scans. Fitting results are tabulated in MCMC_10ks200w.csv The python scripts require the python packages numpy, scipy, silx and refnxFor data reduction, unpackage raw.zip. script data_reduction.ipynb performs the data reduction.Detector calibration of the Eiger 2X was performed using routines of the GSASII software (Toby, B. H., & Von Dreele, R. B. (2013). “GSAS-II: the genesis of a modern open-source all purpose crystallography software package”. J. Appl. Cryst., 46(2), 544-549. DOI: 10.1107/S0021889813003531). GSASII install location at "~/GSASII/" is used but can be changed in the script. exported_fits/orso_converter.ipynb converts datasets in the ORSO .ort and Nexus .h5 formats. This script requires orsopy (www.reflectometry.org/orsopy/) pre_fitter.py fits the data (.csv files) using refnx with differential evolution. 4 different fitting methods are used for comparison: Untransformed, log-transformed, Anscombe-transformed and using the Poisson log-likelihood MCMC_sampler.py performs MCMC sampling on the fits. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III beamline P08. We thank Federal Ministry of Education and Research (BMBF) of Germany for funding Eiger2 1M detector via ErUM Pro 05K19FK2 (Murphy, CAU Kiel).