The CoWork webinar series is dedicated to the exploitation of the coherence properties of X-rays for advanced materials characterization, with a special focus on inverse microscopy techniques, such as Coherent Diffraction Imaging (CDI), Ptychography and Holography. It is an introduction to Coherent X-ray imaging methods to facilitate the access to advanced microscopy techniques to new users and it welcomes all researchers intrigued by the spectacular coherence properties of X-rays produced at modern synchrotron sources – of which MAX IV is a first example.
What: A CoWork DUO webinar on tele-ptychography
When: Thursday May 20, 15.00 - 17.00
Link to the recorded webinar: https://www.linxs.se/educational/x-ray-ptychographic-topography-a-new-tool-for-strain-imaging-diffraction-of-x-ray-by-thin-perfect-crystals
15:00 - 15:40 Speaker: Mariana Verezhak - X-ray ptychographic topography, a new tool for strain imaging
15:40 - 16:00 Questions & Discussion
16:00 - 16:40 Speaker: Angel Rodriguez-Fernandez - Diffraction of X-ray by thin perfect crystals
16:40 - 17:00 Questions & Discussion
Bio of Mariana Verezhak
Mariana Verezhak graduated from Kyiv Polytechnic Institute (Ukraine) with a BSc degree and qualification of Engineer in Materials Science. She then simultaneously obtained her MSc degree from Kyiv Polytechnic Institute and Rennes University (France), participating in the MaMaSELF Erasmus Mundus Program (master in Materials Science exploring large-scale facilities). She has undertaken several scientific internships: conducting first principles studies of graphene/metal interfaces at the National Institute for Materials Science of Japan; studying Si/Metal thin films by secondary neutral mass spectroscopy and atomic probe tomography at University of Debrecen (Hungary); and performed Inelastic neutron and X-ray scattering investigations of quasicrystal phason modes at the Institute of Physics of Rennes (France), thanks to various research grants she obtained. With the nanoscience foundation grant, she completed her PhD at the Laboratory of Interdisciplinary Physics of Grenoble, while occupying a position of visiting scientist at the ESRF, ID13 beamline. During her PhD she studied bone tissue at multi-length scales via coherent diffraction imaging, ptychography, small-angle X-ray scattering and transmission electron microscopy. During last 4 years, she is a post-doc at Paul Scherrer Institute, cSAXS beamline, thanks to the PSI Fellow Marie Curie and European Union's Horizon 2020 grant. She is responsible for user support at the beamline, and has developed ptychographic topography, a novel high-resolution strain imaging technique, as well as continuing her investigations of bone tissue by correlative study with small angle X-ray scattering tensor tomography and ptychographic tomography.
Bio of Angel Rodriguez-Fernandez
Angel Rodriguez-Fernandez obtained his PhD degree in the field of condense matter physics from the University of Oviedo (Spain), where he did also his BSc degree in physics and Master in Materials Science. During his PhD he performed two stages of 3 months each at Cornell High Energy Synchrotron Source, where he got in touch with the field of dynamical diffraction. He did a first postdoc in the SwissFEL project at the Paul Scherrer Institute, Switzerland, working in the self-seeding design of the beamline Aramis, trying to understand the spatiotemporal coupling of diffracted X-rays by thin perfect crystals. After, he joined as postdoctoral researcher the NanoMAX team at MAX IV, Sweden, where he got involved in coherence diffraction experiments with Nanobeams. Since 2019 he works as Instrument Scientist at the European Free Electron laser, Germany, at the Materials Imaging and Dynamics instrument in the beamline SASE2 doing user support and commissioning.
Abstract (Mariana Verezhak)
Strain and defects in crystalline materials are responsible for the distinct mechanical, electric and magnetic properties of a desired material, making their study an essential task in material characterization, fabrication and design. Existing techniques for the visualization of strain fields, such as transmission electron microscopy and diffraction, are destructive and limited to thin slices of the materials. On the other hand, non-destructive X-ray imaging methods either have a reduced resolution or are not robust enough for a broad range of applications. In this talk I will present X-ray ptychographic topography, a new method for strain imaging with the resolution of tens of nanometers, and demonstrate its use on an InSb micro-pillar after micro-compression, where the strained region is visualized. I will describe the experiment performed in both transmission and diffraction geometry and show how X-ray ptychographic topography proves itself as a robust non-destructive approach for the imaging of strain fields within bulk crystalline specimens with a spatial resolution of a few tens of nanometers.
Abstract (Angel Rodriguez-Fernandez)
The emergence of 4th generation synchrotron sources based on low-emittance rings and of spatially coherent X-ray Free Electron Lasers (XFELs) based on self-amplified spontaneous emission, open a new era in the study of high coherence materials, such as perfect crystals, using high coherence probes. Recent years have seen an increase in the development and use of coherent X-ray based inverse microscopy techniques, e.g. coherent X-ray diffraction imaging techniques for the study of sub-micron scale crystalline materials. These methods are based on the assumption of a Fourier transform relation between the sample’s electron density and the X-ray scattered field, derived from the socalled kinematical approximation. On the other end, large diffracting single crystals are one of the primary optical elements for X-ray experiments. For these, more complex interactions including multiple diffraction, absorption and refraction effects must be considered, which are well described by the dynamical diffraction theory. Dynamical diffraction can arise already from samples of modest dimensions, i.e. 500 nm. We show that in conjunction with the use of a coherent technique as tele-ptychography and a nanobeam, these dynamical diffracted wavefront can be retrieved. These wavefronts present a spatiotemporal coupling that relates with the energy of the beam, the element and the d-spacing of the material. From this last parameter, strain information can be subtracted for distorted thin single crystals, which translates to a broadening of the temporal diffracted signal, and a change in position of the diffracted propagated maxima. Data collect at NanoMAX beamline, MAX IV, using this experimental approach will be presented and compared with simulations.
Webinar moderators
Members of the organising group.
Please contact either gerardina.carbone@maxiv.lu.se or asa.grunning@linxs.lu.se for any questions.
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