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Crystals
Special Issues
Coherent X-ray Scattering
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Coherent X-ray Scattering

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 17673

Special Issue Editors

Dr. Dina Carbone

E-Mail Website
Guest Editor
MAX IV Laboratory, Lund University, 22100 Lund, Sweden
Interests: structure, strain, and functionality of materials in confinement; coherent X-ray nanobeams; scanning diffraction; inverse microscopy
Dr. Pablo Villanueva-Perez

E-Mail Website
Guest Editor
Synchrotron Radiation Research Department Lund University, Sweden
Interests: coherent imaging; X-ray imaging; synchrotron radiation; XFELs

Special Issue Information

Dear Colleagues,

Coherent X-rays have been demonstrated to be a powerful tool to investigate nanoscale materials. The interference patterns created by the scattering of coherent waves from a material, both in the near and far field, contain a wealth of information that can be exploited in many different ways to reveal information about its static and dynamical structure. Alongside the rich details carried by coherent x-ray scattering comes the complexity of the algorithms exploited to retrieve information, the high demands on data quality and experiment control, and the low availability of highly coherent X-ray beams. For these reasons, the community around coherence has remained a small niche for a long time, and the incubation time for the methods to become widely available has been unusually long.

The recent availability of coherent X-ray beams at third-generation synchrotron sources, by the simple application of spatial and temporal filters (i.e., pinholes and monochromators), has underpinned the development of diverse methods to fully exploit their potential and increased the community of researchers interested in their application. Coherence has become the crucial property of X-ray beams at new generation sources. X-ray free electron laser (XFELs) sources are founded on the promise of resolving non-crystallized molecules by the inversion of coherent diffraction patterns before the sample is destroyed by the intense pulse, as well as accessing the dynamics of materials at femto-second time scales. In a similar manner, the main drive for the science developed at diffraction limited storage rings (DLSR) sources is the exploitation of coherence for imaging smaller and smaller structures and accessing dynamics of materials at smaller time-scales. Finally, a growing interest in the exploitation of highly coherent X-rays is arising within a scientific community beyond method-development ’experts’, for whom coherence can provide crucial information for the understanding of subtle structural effects or advanced material functionality.

This Special Issue is intended to collect and promulgate scientific results to illustrate the variety of possible applications of coherent X-rays and provide a measure of the growing community utilizing them. We welcome contributions from a broad spectrum of topics, that include applications of established methods to systems –not limited to crystals, advancement of existing approaches and presentation of early developments or “nascent” approaches, proofs-of-concept or theoretical speculations awaiting experimental proofs.

The hope is that this issue, by assembling a large variety of results, serves also to increase their visibility and help to nurture this emerging community.

Dr. Carbone Dina
Dr. Pablo Villanueva-Perez
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • coherent X-rays
  • diffraction
  • scattering
  • inversion methods
  • imaging
  • XPCS
  • dynamics
  • phase contrast XFELs
  • DLSRs

Published Papers (6 papers)

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Research

10 pages, 2282 KiB  
Article
Simultaneous Multi-Bragg Peak Coherent X-ray Diffraction Imaging
by Florian Lauraux, Stéphane Labat, Sarah Yehya, Marie-Ingrid Richard, Steven J. Leake, Tao Zhou, Jean-Sébastien Micha, Odile Robach, Oleg Kovalenko, Eugen Rabkin, Tobias U. Schülli, Olivier Thomas and Thomas W. Cornelius
Crystals 2021, 11(3), 312; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11030312 - 22 Mar 2021
Cited by 6 | Viewed by 2634
Abstract
The simultaneous measurement of two Bragg reflections by Bragg coherent X-ray diffraction is demonstrated on a twinned Au crystal, which was prepared by the solid-state dewetting of a 30 nm thin gold film on a sapphire substrate. The crystal was oriented on a [...] Read more.
The simultaneous measurement of two Bragg reflections by Bragg coherent X-ray diffraction is demonstrated on a twinned Au crystal, which was prepared by the solid-state dewetting of a 30 nm thin gold film on a sapphire substrate. The crystal was oriented on a goniometer so that two lattice planes fulfill the Bragg condition at the same time. The Au 111 and Au 200 Bragg peaks were measured simultaneously by scanning the energy of the incident X-ray beam and recording the diffraction patterns with two two-dimensional detectors. While the former Bragg reflection is not sensitive to the twin boundary, which is oriented parallel to the crystal–substrate interface, the latter reflection is only sensitive to one part of the crystal. The volume ratio between the two parts of the twinned crystal is about 1:9, which is also confirmed by Laue microdiffraction of the same crystal. The parallel measurement of multiple Bragg reflections is essential for future in situ and operando studies, which are so far limited to either a single Bragg reflection or several in series, to facilitate the precise monitoring of both the strain field and defects during the application of external stimuli. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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14 pages, 1341 KiB  
Article
Detector Tilt Considerations in Bragg Coherent Diffraction Imaging: A Simulation Study
by Siddharth Maddali, Marc Allain, Peng Li, Virginie Chamard and Stephan O. Hruszkewycz
Crystals 2020, 10(12), 1150; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10121150 - 17 Dec 2020
Viewed by 2683
Abstract
This paper addresses the three-dimensional signal distortion and image reconstruction issues in X-ray Bragg coherent diffraction imaging (BCDI) in the event of a general non-orthogonal orientation of the area detector with respect to the diffracted beam. Growing interest in novel BCDI adaptations at [...] Read more.
This paper addresses the three-dimensional signal distortion and image reconstruction issues in X-ray Bragg coherent diffraction imaging (BCDI) in the event of a general non-orthogonal orientation of the area detector with respect to the diffracted beam. Growing interest in novel BCDI adaptations at fourth-generation synchrotron light sources has necessitated improvisations in the experimental configuration and the subsequent data analysis. One such possibly unavoidable improvisation that is envisioned in this paper is a photon-counting area detector whose face is tilted away from the perpendicular to the Bragg-diffracted beam during the acquisition of the coherent diffraction signal. We describe a likely circumstance in which one would require such a detector configuration, along with the experimental precedent at third-generation synchrotrons. Using physically accurate diffraction simulations from synthetic scatterers in the presence of such tilted detectors, we analyze the general nature of the observed signal distortion qualitatively and quantitatively and provide a prescription to correct for it during image reconstruction. Our simulations and reconstructions are based on an adaptation of the known theory of BCDI sampling geometry, as well as the recently developed projection-based methods of wavefield propagation. Such configurational modifications and their numerical remedies are potentially valuable in realizing unconventional coherent diffraction measurement geometries, eventually paving the way for the integration of BCDI into new material characterization experiments at next-generation light sources. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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15 pages, 1844 KiB  
Article
The Effect of Intensity Fluctuations on Sequential X-ray Photon Correlation Spectroscopy at the X-ray Free Electron Laser Facilities
by Yue Cao, Dina Sheyfer, Zhang Jiang, Siddharth Maddali, Hoydoo You, Bi-Xia Wang, Zuo-Guang Ye, Eric M. Dufresne, Hua Zhou, G. Brian Stephenson and Stephan O. Hruszkewycz
Crystals 2020, 10(12), 1109; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10121109 - 04 Dec 2020
Cited by 4 | Viewed by 2629
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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16 pages, 5199 KiB  
Article
X-Ray Photon Correlation Spectroscopy with Coherent Nanobeams: A Numerical Study
by Oier Bikondoa and Dina Carbone
Crystals 2020, 10(9), 766; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090766 - 29 Aug 2020
Cited by 6 | Viewed by 3256
Abstract
X-ray photon correlation spectroscopy accesses a wide variety of dynamic phenomena at the nanoscale by studying the temporal correlations among photons that are scattered by a material in dynamical equilibrium when it is illuminated with a coherent X-ray beam. The information that is [...] Read more.
X-ray photon correlation spectroscopy accesses a wide variety of dynamic phenomena at the nanoscale by studying the temporal correlations among photons that are scattered by a material in dynamical equilibrium when it is illuminated with a coherent X-ray beam. The information that is obtained is averaged over the illuminated area, which is generally of the order of several square microns. We propose here that more local information can be obtained by using nanobeams with great potential for the study of heterogeneous systems and show the feasibility of this approach with the support of numerical simulations. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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14 pages, 2863 KiB  
Article
Nanoscale Mapping of Heterogeneous Strain and Defects in Individual Magnetic Nanocrystals
by Xiaowen Shi, Ross Harder, Zhen Liu, Oleg Shpyrko, Eric Fullerton, Boris Kiefer and Edwin Fohtung
Crystals 2020, 10(8), 658; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10080658 - 31 Jul 2020
Cited by 5 | Viewed by 2697
Abstract
We map the three-dimensional strain heterogeneity within a single core-shell Ni nanoparticle using Bragg coherent diffractive imaging. We report the direct observation of both uniform displacements and strain within the crystalline core Ni region. We identify non-uniform displacements and dislocation morphologies across the [...] Read more.
We map the three-dimensional strain heterogeneity within a single core-shell Ni nanoparticle using Bragg coherent diffractive imaging. We report the direct observation of both uniform displacements and strain within the crystalline core Ni region. We identify non-uniform displacements and dislocation morphologies across the core–shell interface, and within the outer shell at the nanoscale. By tracking individual dislocation lines in the outer shell region, and comparing the relative orientation between the Burgers vector and dislocation lines, we identify full and partial dislocations. The full dislocations are consistent with elasticity theory in the vicinity of a dislocation while the partial dislocations deviate from this theory. We utilize atomistic computations and Landau–Lifshitz–Gilbert simulation and density functional theory to confirm the equilibrium shape of the particle and the nature of the (111) displacement field obtained from Bragg coherent diffraction imaging (BCDI) experiments. This displacement field distribution within the core-region of the Ni nanoparticle provides a uniform distribution of magnetization in the core region. We observe that the absence of dislocations within the core-regions correlates with a uniform distribution of magnetization projections. Our findings suggest that the imaging of defects using BCDI could be of significant importance for giant magnetoresistance devices, like hard disk-drive read heads, where the presence of dislocations can affect magnetic domain wall pinning and coercivity. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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9 pages, 1887 KiB  
Article
Unusual Breathing Behavior of Optically Excited Barium Titanate Nanocrystals
by Jiecheng Diao, Mathew Cherukara, Ross Harder, Xiaojing Huang, Fucai Zhang, Bo Chen, Andrew Ulvestad, Sanghoon Song, Diling Zhu, David Keen and Ian Robinson
Crystals 2020, 10(5), 365; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10050365 - 01 May 2020
Cited by 1 | Viewed by 2825
Abstract
Coherent X-ray diffraction patterns were recorded by using an X-ray free-electron laser to illuminate barium titanate nanocrystals as a function of time delay after laser excitation. Rather than seeing any significant thermal expansion effects, the diffraction peaks were found to move perpendicular to [...] Read more.
Coherent X-ray diffraction patterns were recorded by using an X-ray free-electron laser to illuminate barium titanate nanocrystals as a function of time delay after laser excitation. Rather than seeing any significant thermal expansion effects, the diffraction peaks were found to move perpendicular to the momentum transfer direction. This suggests a laser driven rotation of the crystal lattice, which is delayed by the aggregated state of the crystals. Internal deformations associated with crystal contacts were also observed. Full article
(This article belongs to the Special Issue Coherent X-ray Scattering)
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