On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

Bikondoa, Oier

doi:10.1107/s1600576717000577

Cited by 38 publications

(37 citation statements)

References 45 publications

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“…with the ensemble average h:::i performed over all the pixels belonging to the same q-value. C(t 1 , t 1 + t) holds important information when the investigated dynamics are not ergodic, enabling additional insight into out-of equilibrium conditions (Bikondoa, 2017;Madsen et al, 2010). However, if the dynamics are stationary the correlations will depend solely on the lag time t = t 2 À t 1 , and with an additional time average of the two-time matrix it is possible to extract the correlation function g 2 (t) À1.…”

Section: Methodsmentioning

confidence: 99%

Microsecond hydrodynamic interactions in dense colloidal dispersions probed at the European XFEL

Dallari

Jain

Sikorski

et al. 2021

IUCrJ

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Many soft-matter systems are composed of macromolecules or nanoparticles suspended in water. The characteristic times at intrinsic length scales of a few nanometres fall therefore in the microsecond and sub-microsecond time regimes. With the development of free-electron lasers (FELs) and fourth-generation synchrotron light-sources, time-resolved experiments in such time and length ranges will become routinely accessible in the near future. In the present work we report our findings on prototypical soft-matter systems, composed of charge-stabilized silica nanoparticles dispersed in water, with radii between 12 and 15 nm and volume fractions between 0.005 and 0.2. The sample dynamics were probed by means of X-ray photon correlation spectroscopy, employing the megahertz pulse repetition rate of the European XFEL and the Adaptive Gain Integrating Pixel Detector. We show that it is possible to correctly identify the dynamical properties that determine the diffusion constant, both for stationary samples and for systems driven by XFEL pulses. Remarkably, despite the high photon density the only observable induced effect is the heating of the scattering volume, meaning that all other X-ray induced effects do not influence the structure and the dynamics on the probed timescales. This work also illustrates the potential to control such induced heating and it can be predicted with thermodynamic models.

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Section: Methodsmentioning

confidence: 99%

Microsecond hydrodynamic interactions in dense colloidal dispersions probed at the European XFEL

Dallari

Jain

Sikorski

et al. 2021

IUCrJ

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“…If the sample dynamics change during the XPCS series, the g 2 -function in Equation (1) will not detect the dynamics of the sample accurately because of the averaging over time t. In order to quantity such dynamical heterogeneities, the two-time correlation C(q, t 1 , t 2 ) = I(q, t 1 )I(q, t 2 ) pix I(q, t 1 ) pix I(q, t 2 ) pix (7) can be used [45,46]. It calculates the correlation between two patterns of the series at times t 1 and t 2 averaged over all detector pixels of same q without any time averaging.…”

Section: Higher-order Correlationsmentioning

confidence: 99%

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

2021

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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.

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“…The out-of-equilibrium behaviour generally associated with colloidal gels and other soft disordered solids is captured by the instantaneous two-times correlation function, 3,11,[41][42][43][44][45] ,…”

Section: Direction-dependent Intensity Correlation Functionsmentioning

confidence: 99%

Anisotropic and heterogeneous dynamics in an aging colloidal gel

et al. 2020

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On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

Cited by 38 publications

References 45 publications

Microsecond hydrodynamic interactions in dense colloidal dispersions probed at the European XFEL

Microsecond hydrodynamic interactions in dense colloidal dispersions probed at the European XFEL

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

Anisotropic and heterogeneous dynamics in an aging colloidal gel

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