scholarly journals The Effect of Intensity Fluctuations on Sequential X-ray Photon Correlation Spectroscopy at the X-ray Free Electron Laser Facilities

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1109
Author(s):  
Yue Cao ◽  
Dina Sheyfer ◽  
Zhang Jiang ◽  
Siddharth Maddali ◽  
Hoydoo You ◽  
...  
Keyword(s):  
Time Scales ◽  
Free Electron ◽  
Free Electron Laser ◽  
Photon Correlation Spectroscopy ◽  
Signal To Noise Ratio ◽  
Correlation Spectroscopy ◽  
Signal To Noise ◽  
Photon Correlation ◽  
X Ray ◽  
Intensity Fluctuations

How materials evolve at thermal equilibrium and under external excitations at small length and time scales is crucial to the understanding and control of material properties. X-ray photon correlation spectroscopy (XPCS) at X-ray free electron laser (XFEL) facilities can in principle capture dynamics of materials that are substantially faster than a millisecond. However, the analysis and interpretation of XPCS data is hindered by the strongly fluctuating X-ray intensity from XFELs. Here we examine the impact of pulse-to-pulse intensity fluctuations on sequential XPCS analysis. We show that the conventional XPCS analysis can still faithfully capture the characteristic time scales, but with substantial decrease in the signal-to-noise ratio of the g2 function and increase in the uncertainties of the extracted time constants. We also demonstrate protocols for improving the signal-to-noise ratio and reducing the uncertainties.

scholarly journals From Femtoseconds to Hours–Measuring Dynamics over 18 Orders of Magnitude with Coherent X-rays

2021 ◽  
Vol 11 (13) ◽  
pp. 6179
Author(s):  
Felix Lehmkühler ◽  
Wojciech Roseker ◽  
Gerhard Grübel
Keyword(s):  
Time Scales ◽  
Free Electron Laser ◽  
Photon Correlation Spectroscopy ◽  
Signal To Noise Ratio ◽  
Coherent Scattering ◽  
Correlation Spectroscopy ◽  
X Rays ◽  
Photon Correlation ◽  
X Ray ◽  
Scattering Technique

X-ray photon correlation spectroscopy (XPCS) enables the study of sample dynamics between micrometer and atomic length scales. As a coherent scattering technique, it benefits from the increased brilliance of the next-generation synchrotron radiation and Free-Electron Laser (FEL) sources. In this article, we will introduce the XPCS concepts and review the latest developments of XPCS with special attention on the extension of accessible time scales to sub-μs and the application of XPCS at FELs. Furthermore, we will discuss future opportunities of XPCS and the related technique X-ray speckle visibility spectroscopy (XSVS) at new X-ray sources. Due to its particular signal-to-noise ratio, the time scales accessible by XPCS scale with the square of the coherent flux, allowing to dramatically extend its applications. This will soon enable studies over more than 18 orders of magnitude in time by XPCS and XSVS.

scholarly journals Sequential Single Shot X-ray Photon Correlation Spectroscopy at the SACLA Free Electron Laser

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Felix Lehmkühler ◽  
Paweł Kwaśniewski ◽  
Wojciech Roseker ◽  
Birgit Fischer ◽  
Martin A. Schroer ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Photon Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Single Shot ◽  
Photon Correlation ◽  
X Ray

scholarly journals X-ray photon correlation spectroscopy of protein dynamics at nearly diffraction-limited storage rings

IUCrJ ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 794-803 ◽  
Author(s):  
Johannes Möller ◽  
Michael Sprung ◽  
Anders Madsen ◽  
Christian Gutt
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Signal To Noise Ratio ◽  
Protein Molecule ◽  
Storage Rings ◽  
Correlation Spectroscopy ◽  
Biological Macromolecules ◽  
Photon Correlation ◽  
X Ray ◽  
Order Of Magnitude ◽  
New Generation

This study explores the possibility of measuring the dynamics of proteins in solution using X-ray photon correlation spectroscopy (XPCS) at nearly diffraction-limited storage rings (DLSRs). We calculate the signal-to-noise ratio (SNR) of XPCS experiments from a concentrated lysozyme solution at the length scale of the hydrodynamic radius of the protein molecule. We take into account limitations given by the critical X-ray dose and find expressions for the SNR as a function of beam size, sample-to-detector distance and photon energy. Specifically, we show that the combined increase in coherent flux and coherence lengths at the DLSR PETRA IV yields an increase in SNR of more than one order of magnitude. The resulting SNR values indicate that XPCS experiments of biological macromolecules on nanometre length scales will become feasible with the advent of a new generation of synchrotron sources. Our findings provide valuable input for the design and construction of future XPCS beamlines at DLSRs.

Effect of radiation damage and illumination variability on signal-to-noise ratio in X-ray free-electron laser single-particle imaging

2020 ◽  
Vol 76 (6) ◽  
pp. 664-676
Author(s):  
Timur E. Gureyev ◽  
Alexander Kozlov ◽  
Andrew J. Morgan ◽  
Andrew V. Martin ◽  
Harry M. Quiney
Keyword(s):  
Radiation Damage ◽  
Free Electron ◽  
Free Electron Laser ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Incident Intensity ◽  
Temporal Behaviour ◽  
X Ray ◽  
Noise Ratio ◽  
Sample Reconstruction

The deterioration of both the signal-to-noise ratio and the spatial resolution in the electron-density distribution reconstructed from diffraction intensities collected at different orientations of a sample is analysed theoretically with respect to the radiation damage to the sample and the variations in the X-ray intensities illuminating different copies of the sample. The simple analytical expressions and numerical estimates obtained for models of radiation damage and incident X-ray pulses may be helpful in planning X-ray free-electron laser (XFEL) imaging experiments and in analysis of experimental data. This approach to the analysis of partially coherent X-ray imaging configurations can potentially be used for analysis of other forms of imaging where the temporal behaviour of the sample and the incident intensity during exposure may affect the inverse problem of sample reconstruction.

scholarly journals Noise reduction in X-ray photon correlation spectroscopy with convolutional neural networks encoder–decoder models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tatiana Konstantinova ◽  
Lutz Wiegart ◽  
Maksim Rakitin ◽  
Anthony M. DeGennaro ◽  
Andi M. Barbour
Keyword(s):  
Experimental Data ◽  
Correlation Functions ◽  
Photon Correlation Spectroscopy ◽  
Noise Removal ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
Time Correlation Functions ◽  
Signal To Noise ◽  
Photon Correlation ◽  
X Ray

AbstractLike other experimental techniques, X-ray photon correlation spectroscopy is subject to various kinds of noise. Random and correlated fluctuations and heterogeneities can be present in a two-time correlation function and obscure the information about the intrinsic dynamics of a sample. Simultaneously addressing the disparate origins of noise in the experimental data is challenging. We propose a computational approach for improving the signal-to-noise ratio in two-time correlation functions that is based on convolutional neural network encoder–decoder (CNN-ED) models. Such models extract features from an image via convolutional layers, project them to a low dimensional space and then reconstruct a clean image from this reduced representation via transposed convolutional layers. Not only are ED models a general tool for random noise removal, but their application to low signal-to-noise data can enhance the data’s quantitative usage since they are able to learn the functional form of the signal. We demonstrate that the CNN-ED models trained on real-world experimental data help to effectively extract equilibrium dynamics’ parameters from two-time correlation functions, containing statistical noise and dynamic heterogeneities. Strategies for optimizing the models’ performance and their applicability limits are discussed.

scholarly journals Techniques to characterize dynamics in biomaterials microenvironments: XPCS and microrheology of alginate/PEO–PPO–PEO hydrogels

Soft Matter ◽  
2021 ◽  
Author(s):  
Suan P. Quah ◽  
Yugang Zhang ◽  
Andrei Fluerasu ◽  
Xiaoxi Yu ◽  
Bingqian Zheng ◽  
...  
Keyword(s):  
Time Scales ◽  
Photon Correlation Spectroscopy ◽  
Soft Materials ◽  
Correlation Spectroscopy ◽  
Photon Correlation ◽  
X Ray ◽  
Cell Material ◽  
Cell Material Interactions ◽  
Insight Into

X-ray photon correlation spectroscopy (XPCS) experiments provide insight into microscale dynamics of soft materials and biomaterials, differing from macroscale rheology, on time scales relevant to some cell-material interactions.

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