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Science Seminars

XFEL imaging studies of irreversible phenomena in materials science

by Prof. Henning Friis Poulsen (The 3D Imaging center, Physics Department, Technical University of Denmark)

→ Europe/Berlin
XHQ / E1.173 (22869 Schenefeld)

XHQ / E1.173

22869 Schenefeld

Holzkoppel 4
Description

The mechanical and many physical properties of crystalline materials are governed by the microstructure evolution. The underlying events can only be studied in a representative way in bulk materials and often take place on timescales too fast for present synchrotron imaging. Examples include dislocation interactions during plastic deformation, martensitic transformations, domain switching, acoustic wave propagation, dielectric breakdown and failure. These processes are typically irreversible, stochastic and heterogeneous, which makes them difficult to capture with conventional pump–probe schemes or with diffraction methods that average over many microstructural elements. In this seminar I will argue that this is a natural opportunity for XFELs: the time structure and pulse intensity of XFELs should be used to take real-space snapshots of microstructure and local strain during real life processing.

Dark-field X-ray microscopy, DFXM, is a full-field diffraction imaging technique in which an objective lens placed in the diffracted beam forms a magnified image of a selected grain, domain or defect structure. It combines hard-X-ray penetration, sensitivity to lattice orientation and strain and a field of view large enough to capture representative microstructure. At XFELs, DFXM can image an entire microstructural layer within the duration of one pulse. As a demonstration I will showcase the imaging acoustic waves propagating in diamond, where longitudinal and transverse wave packets, branching and dissipation could be followed inside a millimetre-sized crystal. 

I will then outline a suggestion for a dedicated Ultrafast X-ray Microscope at the European XFEL, with two complementary modes: pump–probe imaging for reversible dynamics, and bunch-train imaging for irreversible events at approximately 200 ns and above. I will discuss technical challenges and give examples of science cases. 

  1. H. Simons, A. King, W. Ludwig, C. Detlefs, W. Pantleon, S. Schmidt, F. Stöhr, I. Snigireva, A. Snigirev, H. F. Poulsen, “Dark-field X-ray microscopy for multiscale structural characterization,” Nature Communications 6, 6098 (2015). DOI: 10.1038/ncomms7098.
  2. H. F. Poulsen, A. C. Jakobsen, H. Simons, S. R. Ahl, P. K. Cook, C. Detlefs, “X-ray diffraction microscopy based on refractive optics,” Journal of Applied Crystallography 50, 1441–1456 (2017). DOI: 10.1107/S1600576717011037.
  3. T. S. Holstad, L. E. Dresselhaus-Marais, T. M. Ræder, et al., “Real-time imaging of acoustic waves in bulk materials with X-ray microscopy,” PNAS 120, e2307049120 (2023). DOI: 10.1073/pnas.2307049120.
  4. S. J. Irvine, K. Katagiri, T. M. Ræder, et al., “Dark-field x-ray microscopy for 2D and 3D imaging of microstructural dynamics at the European x-ray free-electron laser,” Journal of Applied Physics 137, 053106 (2025). DOI: 10.1063/5.0239034

 

 
 

Join Zoom Meeting
https://xfel.zoom.us/j/62269153362?pwd=dMe4BHKOKKNBx9p2189G0yixoAKtR5.1

Meeting ID: 622 6915 3362
Passcode: 360297

Organized by Sakura Pascarelli

 

 

Organised by

Sakura Pascarelli

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