scholarly journals Non-equilibrium processes in martensitic phase transformations by X-ray photon correlation spectroscopy

2015 ◽  
Vol 1754 ◽  
pp. 141-146
Author(s):  
Michael Widera ◽  
Uwe Klemradt
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
X Rays ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Dynamics ◽  
Speckle Patterns ◽  
Martensitic Phase Transformations ◽  
Non Equilibrium

ABSTRACTThrough undulator sources at 3rd generation synchrotrons, highly coherent X-rays with sufficient flux are nowadays routinely available, which allow carrying over photon correlation spectroscopy (PCS) from visible light to the X-ray regime. X-ray photon correlation spectroscopy (XPCS) is based on the auto-correlation of X-ray speckle patterns during the temporal evolution of a material and provides access both to equilibrium and non-equilibrium properties of materials at the Angstrom scale. Owing to technical limitations (detector readout), XPCS has typically been used for the detection of slow dynamics on the scale of seconds. The variety of scattering geometries employed in conventional X-ray analysis can be combined with XPCS. In this work, we report on bulk diffraction (XRD) used to study the prototypical shape memory alloy Ni63Al37 undergoing a structural, diffusionless (martensitic) transformation. Two-time correlation functions reveal non-equilibrium dynamics superimposed with microstructural avalanches.

scholarly journals Ferroelectric domain wall dynamics characterized with X-ray photon correlation spectroscopy

2018 ◽  
Vol 115 (29) ◽  
pp. E6680-E6689 ◽  
Author(s):  
Semën Gorfman ◽  
Alexei A. Bokov ◽  
Arman Davtyan ◽  
Mario Reiser ◽  
Yujuan Xie ◽  
...  
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
Photon Correlation Spectroscopy ◽  
Domain Wall Motion ◽  
Correlation Spectroscopy ◽  
X Rays ◽  
Photon Correlation ◽  
X Ray ◽  
Domain Wall Dynamics ◽  
Speckle Patterns

Technologically important properties of ferroic materials are determined by their intricate response to external stimuli. This response is driven by distortions of the crystal structure and/or by domain wall motion. Experimental separation of these two mechanisms is a challenging problem which has not been solved so far. Here, we apply X-ray photon correlation spectroscopy (XPCS) to extract the contribution of domain wall dynamics to the overall response. Furthermore, we show how to distinguish the dynamics related to the passing of domain walls through the periodic (Peierls) potential of the crystal lattice and through the random potential caused by lattice defects (pinning centers). The approach involves the statistical analysis of correlations between X-ray speckle patterns produced by the interference of coherent synchrotron X-rays scattered from different nanosize volumes of the crystal and identification of Poisson-type contribution to the statistics. We find such a contribution in the thermally driven response of the monoclinic phase of a ferroelectric PbZr0.55Ti0.45O3 crystal and calculate the number of domain wall jumps in the studied microvolume.

Development of ultra-small-angle X-ray scattering–X-ray photon correlation spectroscopy

2011 ◽  
Vol 44 (1) ◽  
pp. 200-212 ◽  
Author(s):  
F. Zhang ◽  
A. J. Allen ◽  
L. E. Levine ◽  
J. Ilavsky ◽  
G. G. Long ◽  
...  
Keyword(s):  
Small Angle ◽  
Photon Correlation Spectroscopy ◽  
Coherent Scattering ◽  
Correlation Spectroscopy ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Dynamics ◽  
X Ray Scattering ◽  
Non Equilibrium ◽  
Ray Scattering

This paper describes the development of ultra-small-angle X-ray scattering–X-ray photon correlation spectroscopy (USAXS–XPCS). This technique takes advantage of Bonse–Hart crystal optics and is capable of probing the long-time-scale equilibrium and non-equilibrium dynamics of optically opaque materials with prominent features in a scattering vector range between those of dynamic light scattering and conventional XPCS. Instrumental parameters for optimal coherent-scattering operation are described. Two examples are offered to illustrate the applicability and capability of USAXS–XPCS. The first example concerns the equilibrium dynamics of colloidal dispersions of polystyrene microspheres in glycerol at 10, 15 and 20% volume concentrations. The temporal intensity autocorrelation analysis shows that the relaxation time of the microspheres decays monotonically as the scattering vector increases. The second example concerns the non-equilibrium dynamics of a polymer nanocomposite, for which it is demonstrated that USAXS–XPCS can reveal incipient dynamical changes not observable by other techniques.

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

2017 ◽  
Vol 50 (2) ◽  
pp. 357-368 ◽  
Author(s):  
Oier Bikondoa
Keyword(s):  
Correlation Functions ◽  
Photon Correlation Spectroscopy ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
Time Correlation Functions ◽  
Spectroscopy Data ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Processes ◽  
Time Correlations

Multi-time correlation functions are especially well suited to study non-equilibrium processes. In particular, two-time correlation functions are widely used in X-ray photon correlation experiments on systems out of equilibrium. One-time correlations are often extracted from two-time correlation functions at different sample ages. However, this way of analysing two-time correlation functions is not unique. Here, two methods to analyse two-time correlation functions are scrutinized, and three illustrative examples are used to discuss the implications for the evaluation of the correlation times and functional shape of the correlations.

A novel event correlation scheme for X-ray photon correlation spectroscopy

2012 ◽  
Vol 45 (4) ◽  
pp. 807-813 ◽  
Author(s):  
Y. Chushkin ◽  
C. Caronna ◽  
A. Madsen
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Glassy State ◽  
Correlation Spectroscopy ◽  
Event Correlation ◽  
Photon Correlation ◽  
X Ray ◽  
Wide Range ◽  
Intermediate Scattering Function ◽  
Speckle Patterns ◽  
Laser Sources

X-ray photon correlation spectroscopy (XPCS) was employed to measure the time-dependent intermediate scattering function in an organic molecular glass former. Slow translational dynamics were probed in the glassy state and the correlation functions were calculated from two-dimensional speckle patterns recorded by a CCD detector. The image frames were analysed using a droplet algorithm together with an event correlation scheme. This method provides results analogous to standard intensity correlation algorithms but is much faster, hence addressing the recurrent problem of insufficient computing power for online analysis in XPCS. The event correlator has a wide range of potential future applications at synchrotrons and free-electron laser sources.

Combined measurement of X-ray photon correlation spectroscopy and diffracted X-ray tracking using pink beam X-rays

2013 ◽  
Vol 20 (5) ◽  
pp. 801-804 ◽  
Author(s):  
Yuya Shinohara ◽  
Akira Watanabe ◽  
Hiroyuki Kishimoto ◽  
Yoshiyuki Amemiya
Keyword(s):  
Carbon Black ◽  
Photon Correlation Spectroscopy ◽  
Translational Motion ◽  
Correlation Spectroscopy ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
X Rays ◽  
Photon Correlation ◽  
X Ray ◽  
Styrene Butadiene

Combined X-ray photon correlation spectroscopy (XPCS) and diffracted X-ray tracking (DXT) measurements of carbon-black nanocrystals embedded in styrene–butadiene rubber were performed. From the intensity fluctuation of speckle patterns in a small-angle scattering region (XPCS), dynamical information relating to the translational motion can be obtained, and the rotational motion is observed through the changes in the positions of DXT diffraction spots. Graphitized carbon-black nanocrystals in unvulcanized styrene–butadiene rubber showed an apparent discrepancy between their translational and rotational motions; this result seems to support a stress-relaxation model for the origin of super-diffusive particle motion that is widely observed in nanocolloidal systems. Combined measurements using these two techniques will give new insights into nanoscopic dynamics, and will be useful as a microrheology technique.

scholarly journals Nanosecond X-ray photon correlation spectroscopy using pulse time structure of a storage-ring source

IUCrJ ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 124-130
Author(s):  
Wonhyuk Jo ◽  
Fabian Westermeier ◽  
Rustam Rysov ◽  
Olaf Leupold ◽  
Florian Schulz ◽  
...  
Keyword(s):  
Storage Ring ◽  
Photon Correlation Spectroscopy ◽  
Single Pulse ◽  
Correlation Spectroscopy ◽  
Photon Flux ◽  
Pixel Detector ◽  
Photon Correlation ◽  
X Ray ◽  
Speckle Patterns ◽  
Nanosecond Time Resolution

X-ray photon correlation spectroscopy (XPCS) is a routine technique to study slow dynamics in complex systems at storage-ring sources. Achieving nanosecond time resolution with the conventional XPCS technique is, however, still an experimentally challenging task requiring fast detectors and sufficient photon flux. Here, the result of a nanosecond XPCS study of fast colloidal dynamics is shown by employing an adaptive gain integrating pixel detector (AGIPD) operated at frame rates of the intrinsic pulse structure of the storage ring. Correlation functions from single-pulse speckle patterns with the shortest correlation time of 192 ns have been calculated. These studies provide an important step towards routine fast XPCS studies at storage rings.

scholarly journals Charge-induced equilibrium dynamics and structure at the Ag(001)–electrolyte interface

2015 ◽  
Vol 17 (26) ◽  
pp. 16682-16687 ◽  
Author(s):  
Robert M. Karl Jr. ◽  
Andi Barbour ◽  
Vladimir Komanicky ◽  
Chenhui Zhu ◽  
Alec Sandy ◽  
...  
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Atomic Step ◽  
Applied Potential ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Dynamics ◽  
Step Motion ◽  
Dependent Rate ◽  
Electrolyte Interface

The applied potential dependent rate of atomic step motion of the Ag(001) surface in weak NaF electrolyte has been measured using a new extension of the technique of X-ray Photon Correlation Spectroscopy (XPCS).

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.

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