Coherent X-ray diffraction imaging meets ptychography to study core-shell-shell nanowires

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2317-2322 ◽  
Author(s):  
A. Davtyan ◽  
V. Favre-Nicolin ◽  
R. B. Lewis ◽  
H. Küpers ◽  
L. Geelhaar ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Bragg Reflection ◽  
Rotational Symmetry ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Bottom Part ◽  
X Ray ◽  
Structural Homogeneity ◽  
Diffraction Imaging ◽  
Diffraction Patterns

AbstractWe report on the results of coherent X-ray diffraction imaging (CXDI) and ptychography measurements of two individual core-shell-shell GaAs/(In,Ga)As/GaAs nanowires (NWs) grown by molecular beam epitaxy (MBE) on patterned Si(111) substrate. CXDI at the axial GaAs 111 Bragg reflection was applied at different positions along the NW axis in order to characterize the NWs in terms of structural homogeneity along the radial directions. At each positon 3D reciprocal space maps have been recoded and inverted using phase retrieval algorithms. The CXDI were complemented by 2D ptychography measurements at GaAs 111 Bragg reflection probing the same NWs with respect to their structural homogeneity. Both methods provide structural homogeneity for NW1 and NW2 except at the bottom part of the NWs. In case of NW2 CXDI and ptychography show changes in the structure of the top part of the NW indicated by 60° rotation of the indicated three-fold rotational symmetry in the observed diffraction patterns and changes in the strain field reconstructed from ptychography.

scholarly journals Simultaneous Multi-Bragg Peak Coherent X-ray Diffraction Imaging

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 312
Author(s):  
Florian Lauraux ◽  
Stéphane Labat ◽  
Sarah Yehya ◽  
Marie-Ingrid Richard ◽  
Steven J. Leake ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Volume Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Substrate ◽  
In Series ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Lattice Planes ◽  
Oriented Parallel

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.

scholarly journals Threefold rotational symmetry in hexagonally shaped core–shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging

2017 ◽  
Vol 50 (3) ◽  
pp. 673-680 ◽  
Author(s):  
Arman Davtyan ◽  
Thilo Krause ◽  
Dominik Kriegner ◽  
Ali Al-Hassan ◽  
Danial Bahrami ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Rotational Symmetry ◽  
Core Shell ◽  
The Finite Element Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Threefold Symmetry ◽  
Gaas Nanowires ◽  
Diffraction Imaging ◽  
Scattering Phase

Coherent X-ray diffraction imaging at symmetrichhhBragg reflections was used to resolve the structure of GaAs/In0.15Ga0.85As/GaAs core–shell–shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct the lost phase information. It is demonstrated that the structure of the core–shell–shell nanowire can be identified by means of phase contrast. Interestingly, it is found that both scattered intensity in the (111) plane and the reconstructed scattering phase show an additional threefold symmetry superimposed with the shape function of the investigated hexagonal nanowires. In order to find the origin of this threefold symmetry, elasticity calculations were performed using the finite element method and subsequent kinematic diffraction simulations. These suggest that a non-hexagonal (In,Ga)As shell covering the hexagonal GaAs core might be responsible for the observation.

scholarly journals Multi-wavelength Bragg coherent X-ray diffraction imaging of Au particles

2020 ◽  
Vol 53 (1) ◽  
pp. 170-177 ◽  
Author(s):  
F. Lauraux ◽  
T. W. Cornelius ◽  
S. Labat ◽  
M.-I. Richard ◽  
S. J. Leake ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
High Sensitivity ◽  
Carbon Layer ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multi Wavelength ◽  
Diffraction Imaging ◽  
Diffraction Patterns

Multi-wavelength (mw) Bragg coherent X-ray diffraction imaging (BCDI) is demonstrated on a single Au particle. The multi-wavelength Bragg diffraction patterns are inverted using conventional phase-retrieval algorithms where the dilation of the effective pixel size of a pixelated 2D detector caused by the variation of the X-ray beam energy is mitigated by interpolating the raw data. The reconstructed Bragg electron density and phase field are in excellent agreement with the results obtained from conventional rocking scans of the same particle. Voxel sizes of about 63 nm3 are obtained for reconstructions from both approaches. Phase shifts as small as 0.41 rad, which correspond to displacements of 14 pm and translate into strain resolution better than 10−4 in the Au particle, are resolved. The displacement field changes shape during the experiment, which is well reproduced by finite element method simulations considering an inhomogeneous strained carbon layer deposited on the Au particle over the course of the measurements. These experiments thus demonstrate the very high sensitivity of BCDI and mw-BCDI to strain induced by contaminations. Furthermore, mw-BCDI offers new opportunities for in situ and operando 3D strain imaging in complex sample environments.

IDATENandG-SITENNO: GUI-assisted software for coherent X-ray diffraction imaging experiments and data analyses at SACLA

2014 ◽  
Vol 21 (6) ◽  
pp. 1378-1383 ◽  
Author(s):  
Yuki Sekiguchi ◽  
Masaki Yamamoto ◽  
Tomotaka Oroguchi ◽  
Yuki Takayama ◽  
Shigeyuki Suzuki ◽  
...  
Keyword(s):  
User Interfaces ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Custom Made ◽  
Sample Position ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
User Friendly ◽  
Ccd Detectors

Using our custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors, cryogenic coherent X-ray diffraction imaging experiments have been undertaken at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility. To efficiently perform experiments and data processing, two software suites with user-friendly graphical user interfaces have been developed. The first is a program suite namedIDATEN, which was developed to easily conduct four procedures during experiments: aligning KOTOBUKI-1, loading a flash-cooled sample into the cryogenic goniometer stage inside the vacuum chamber of KOTOBUKI-1, adjusting the sample position with respect to the X-ray beam using a pair of telescopes, and collecting diffraction data by raster scanning the sample with X-ray pulses. NamedG-SITENNO, the other suite is an automated version of the originalSITENNOsuite, which was designed for processing diffraction data. These user-friendly software suites are now indispensable for collecting a large number of diffraction patterns and for processing the diffraction patterns immediately after collecting data within a limited beam time.

Incorporating particle symmetry into orientation determination in single-particle imaging

2018 ◽  
Vol 74 (5) ◽  
pp. 512-517
Author(s):  
Miklós Tegze ◽  
Gábor Bortel
Keyword(s):  
Three Dimensional ◽  
Symmetric Case ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Particle Imaging ◽  
Single Particle Imaging ◽  
Orientation Determination

In coherent-diffraction-imaging experiments X-ray diffraction patterns of identical particles are recorded. The particles are injected into the X-ray free-electron laser (XFEL) beam in random orientations. If the particle has symmetry, finding the orientation of a pattern can be ambiguous. With some modifications, the correlation-maximization method can find the relative orientations of the diffraction patterns for the case of symmetric particles as well. After convergence, the correlation maps show the symmetry of the particle and can be used to determine the symmetry elements and their orientations. The C factor, slightly modified for the symmetric case, can indicate the consistency of the assembled three-dimensional intensity distribution.

scholarly journals Dark-field phase retrieval under the constraint of the Friedel symmetry in coherent X-ray diffraction imaging

2014 ◽  
Vol 22 (23) ◽  
pp. 27892 ◽  
Author(s):  
Amane Kobayashi ◽  
Yuki Sekiguchi ◽  
Yuki Takayama ◽  
Tomotaka Oroguchi ◽  
Masayoshi Nakasako
Keyword(s):  
Phase Retrieval ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Field Phase ◽  
X Ray ◽  
Diffraction Imaging

scholarly journals The influence of strain on image reconstruction in Bragg coherent X-ray diffraction imaging and ptychography

2021 ◽  
Vol 28 (4) ◽  
Author(s):  
Chan Kim ◽  
Markus Scholz ◽  
Anders Madsen
Keyword(s):  
Phase Retrieval ◽  
Superlattice Reflection ◽  
Antiphase Domain ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Boundaries ◽  
Diffraction Imaging ◽  
Highly Strained ◽  
The Impact

A quantitative analysis of the effect of strain on phase retrieval in Bragg coherent X-ray diffraction imaging is reported. It is shown in reconstruction simulations that the phase maps of objects with strong step-like phase changes are more precisely retrieved than the corresponding modulus values. The simulations suggest that the reconstruction precision for both phase and modulus can be improved by employing a modulus homogenization (MH) constraint. This approach was tested on experimental data from a highly strained Fe–Al crystal which also features antiphase domain boundaries yielding characteristic π phase shifts of the (001) superlattice reflection. The impact of MH is significant and this study outlines a successful method towards imaging of strong phase objects using the next generation of coherent X-ray sources, including X-ray free-electron lasers.

scholarly journals Three-dimensional coherent X-ray diffraction imaging via deep convolutional neural networks

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Longlong Wu ◽  
Shinjae Yoo ◽  
Ana F. Suzana ◽  
Tadesse A. Assefa ◽  
Jiecheng Diao ◽  
...  
Keyword(s):  
Transfer Learning ◽  
Phase Retrieval ◽  
Three Dimensional ◽  
Current Phase ◽  
X Ray Diffraction ◽  
Deep Convolutional Neural Networks ◽  
X Ray ◽  
Model Combining ◽  
Diffraction Imaging ◽  
Improved Performance

AbstractAs a critical component of coherent X-ray diffraction imaging (CDI), phase retrieval has been extensively applied in X-ray structural science to recover the 3D morphological information inside measured particles. Despite meeting all the oversampling requirements of Sayre and Shannon, current phase retrieval approaches still have trouble achieving a unique inversion of experimental data in the presence of noise. Here, we propose to overcome this limitation by incorporating a 3D Machine Learning (ML) model combining (optional) supervised learning with transfer learning. The trained ML model can rapidly provide an immediate result with high accuracy which could benefit real-time experiments, and the predicted result can be further refined with transfer learning. More significantly, the proposed ML model can be used without any prior training to learn the missing phases of an image based on minimization of an appropriate ‘loss function’ alone. We demonstrate significantly improved performance with experimental Bragg CDI data over traditional iterative phase retrieval algorithms.

Sign in / Sign up

Export Citation Format

Share Document