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Ptychography is a diffraction-based X-ray microscopy method that can image extended samples quantitatively while remove the resolution limit imposed by image-forming optical elements. As a natural extension of scanning transmission X-ray microscopy (STXM) imaging method, we developed soft X-ray ptychographic coherent diffraction imaging (PCDI) meth...
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... to a power spectral density (PSD) analysis, the image resolution reaches 8.5 nm, much higher than the STXM resolution of 32 nm. Table 1 shows that PCDI has great advantages over STXM not only in spatial resolution, but also in radiation dose and data collection efficiency. The radiation dose is proportional to the exposure time of the sample when the incident beam is stable. ...
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An in-house designed transmission X-ray microscopy (TXM) instrument has been developed and commissioned at beamline BL18B of the Shanghai Synchrotron Radiation Facility (SSRF). BL18B is a hard (5–14 keV) X-ray bending-magnet beamline recently built with sub-20 nm spatial resolution in TXM. There are two kinds of resolution mode: one based on using...
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... More recently, the SSRF commissioned all its second-phase beamlines that employ state-of-the-art undulators to provide significantly higher beam quality. This endeavor will facilitate the development of coherent technology that has already achieved results in coherent diffraction imaging (CDI) and scanning coherent diffraction imaging (scanning CDI or ptychography) at the SSRF [41][42][43]. However, significant progress is yet to be achieved in XPCS experiments. ...
X-ray photon correlation spectroscopy (XPCS) has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities. This technique requires high brilliance and beam coherence, which are not directly available at modern synchrotron beamlines in China. To facilitate future XPCS experiments, we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility (SSRF). Subsequently, we performed XPCS measurements on silica suspensions in glycerol, which were opaque owing to their high concentrations. Images were collected using a high frame rate area detector. A comprehensive analysis was performed, yielding correlation functions and several key dynamic parameters. All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF. Finally, by carefully optimizing the setup and analyzing algorithms, we achieved a time resolution of 2 ms, which enabled the characterization of millisecond dynamics in opaque systems.
... A mathematical algorithm is then used to reconstruct the set of DI into a real space image. [35][36][37][38][39][40][41] Recently, ptychography [36] has been implemented in a number of soft X-ray STXM facilities, including the HERMES beamline at Synchrotron SOLEIL [37,38], the COSMIC beamline at the Advanced Light Source [39,40], the STXM at the Shanghai Synchrotron Radiation Facility [41], and the spectromicroscopy beamline at the Canadian Light Source. [42] Ptychography is implemented in a STXM by replacing the post-specimen single channel detector with an X-ray sensitive camera, for example, the sCMOS camera [43,44] implemented in the STXM at the HERMES beamline of Synchrotron SOLEIL. ...
... A mathematical algorithm is then used to reconstruct the set of DI into a real space image. [35][36][37][38][39][40][41] Recently, ptychography [36] has been implemented in a number of soft X-ray STXM facilities, including the HERMES beamline at Synchrotron SOLEIL [37,38], the COSMIC beamline at the Advanced Light Source [39,40], the STXM at the Shanghai Synchrotron Radiation Facility [41], and the spectromicroscopy beamline at the Canadian Light Source. [42] Ptychography is implemented in a STXM by replacing the post-specimen single channel detector with an X-ray sensitive camera, for example, the sCMOS camera [43,44] implemented in the STXM at the HERMES beamline of Synchrotron SOLEIL. ...
A micro-chip based three-electrode electrochemical reactor enabling controlled, variable electrolyte flow, rapid electrolyte change and applied electrode potentials was used for in-situ soft X-ray spectro-ptychography of Cu particle catalysts under electrochemical CO2 reduction (CO2R) conditions. In comparison to scanning transmission X-ray microscopy (STXM), the spatial resolution was improved by a factor of three through measuring patterns of diffracted photons via spectro-ptychography. We present here a detailed study of how individual cubic Cu particles change morphology and oxidation state as a function of applied potential during CO2R. Quantitative chemical mapping by in-situ spectro-ptychography demonstrated that as-deposited, primarily mixed Cu(I) and Cu(0) particles were completely reduced to pure Cu(0) at an electrode potential of -0.2 VRHE, above the potential at which CO2R commences. At increasingly negative potentials, in the regime of CO2R, these Cu(0) particles underwent morphological changes, losing the initial cubic structure and forming irregular dendritic-like structures. This initial demonstration of in-situ soft X-ray spectro-ptychography sheds insight on the morphological and chemical structural changes of Cu particles in the CO2R regime and paves the way for more detailed in-situ studies of electrochemical materials and processes.
... Finally, the deposited dose on the sample is a major concern when working with ptychography [21,22], because non-crystalline samples need higher exposition compared to crystalline samples, where intensity is added coherently in diffraction peaks [23]. In order to address this issue, Monte Carlo simulations were performed to numerically estimate the delivered dose from the CARNAUBA beam to common samples with high accuracy. ...
Ptychography is an absorption and phase contrast imaging method, via coherent
diffraction and phase retrieval, recently demonstrated in X-rays. An advantage of this technique is the reconstruction of both the sample and the illumination complex functions, with resolution of a few nanometers, without any previous knowledge of them. These characteristics make ptychography one of the most robust and accurate diagnostic methods to assess the amplitude and phase of an X-ray beam of nanometric dimensions.
In this work, we apply wave optics to simulate the ptychography experiment from source to detector. Start-to-end simulations allow one to study how different parameters, either from the source or optical elements, can affect the ptychography experiment. A code for ptychographic phase retrieval based on the ePIE algorithm was implemented and used for the reconstructions with the simulated data. The method was applied to the CARNAÚBA beamline of Sirius, the new Brazilian synchrotron light source, with the objective of quantifying aberrations present in the optical system. Results from geometric and wave optics simulations were used to determine which are the most critical degrees of freedom of the Kirkpatrick-Baez (KB) mirrors system and to establish the alignment tolerances. Aberrations are analyzed both in terms of their effects on the focal spot, with geometric optics, and in terms of the wavefront decomposition in Zernike polynomials.
Finally, the delivered dose rate to different materials is calculated using Monte Carlo
simulation, which dictates the maximum exposure time of the samples to the X-ray beam to prevent radiation damage from occurring. The achieved results will be useful at the alignment procedure of the KB mirrors system, during the commissioning of the beamline. Besides, the methods developed in this work can potentially be used to implement automatic alignment of KB mirrors systems, which can be extended to other nanoprobes in Sirius.
... To the best of the authors' knowledge, COSMIC is the only soft X-ray spectromicroscopic beamline that couples STXM with ptychography and is capable of sharp ptychographic imaging at the energy of 1500-1850 eV (in fifth harmonics) at spatial resolution <10 nm. Other ptychographic imaging microscopy at STXM/ptychography beamlines at other synchrotron facilities were mainly optimized at the energy range of 700-1000 eV (in third harmonics) due to the limitations of their beam brilliance, CCD detectors, microscopic configuration, or optimized algorithm [85][86][87]. Other X-ray absorption beamlines are primarily in the beam energy range of 2-12 keV or higher [88,25], which does not cover the K-edge of major elements of FA, e.g., O, Na, Mg, Al, and Si. ...
Scanning transmission X-ray microscopy (STXM) coupled with ptychographic imaging at Al and Si K-edge is a new probe to the microscale chemistry of heterogenous materials. Here, the combined techniques are applied to study local coordination environment of Fe-rich fly ash (FA). Ptychographic imaging at Al K- and Si K-edge highlights the fine Al- and Si-rich morphological features, respectively, at 6 nm pixel resolution. STXM visualizes the inter- and intra-particle variations in the silicate polymerization degree and two types of Al coordination environment in FA. The Si K-edge of SiO4 connected with four-fold coordinated Al is higher than SiO4 sharing oxygen with six-fold coordinated Al. The result is consistent with bulk nuclear magnetic resonance spectroscopy measurement of the Fe-rich sample which, however, is sensitive to paramagnetic Fe and time-consuming. We demonstrate that the combined method has great potential in the studies of chemically heterogenous aluminosilicates.
Coherent X-ray diffraction imaging (CDI) method is a powerful X-ray imaging technique with high resolution up to nanometer scale. Most of the synchrotron radiation facilities and free electron laser facilities are equipped with this state-of-the-art imaging technique and have made many outstanding achievements in multiple scientific areas. Up to now, although scanning CDI (ptychography) method based on a soft X-ray source has been opened to users, the hard X-ray CDI experimental platform has not been built at Shanghai Synchrotron Radiation Facility (SSRF) which can research some relatively thick specimens and easily extend to three-dimensional imaging. As some new beamlines with undulator source were put into operation recently, it is possible and feasible to build up the CDI experimental platform with hard X-ray. In this article, we report the hard X-ray CDI experimental platform development process and preliminary experimental results of coherent diffraction pattern and image reconstruction at SSRF. Based on the operating BL19U2 biological small-angle X-ray scattering (SAXS) beamline at SSRF, the hard X-ray coherent beam is obtained through effective optical path designation at 12 keV and 13.5 keV. The hard X-ray optimization includes tuning several slits, double crystal monochromator (DCM), horizontal deflection mirror, focusing mirror system and pinhole, etc. Furthermore, hard X-ray CDI experiments are conducted. The spatial coherent length of the incident beam is also measured from the pinhole diffraction pattern. This platform can provide both conventional mode and scanning mode (ptychography) for the coherent diffraction imaging method, and the correct image reconstruction from the experimental diffraction patterns proves that the platform has the experimental capability for hard X-ray CDI. In the conventional forward scattering CDI mode, coherent diffraction patterns of pinhole are collected and used to analyse the coherence property of the optimized X-ray beam. The structure of pinhole is also reconstructed from the diffraction pattern. In the scanning CDI mode, a zone plate is used as a sample. The central area of zone plate is reconstructed correctly. About 90 nm/pixel resolution of reconstruction is achieved which is extremely dependent on the X-ray flux density from the undulator source emission. Hard X-ray CDI experimental platform based on the synchrotron radiation facility is first built in China. It will provide effective software and hardware supporting for the development and application of hard X-ray CDI experiments in China in the future.
