Microscopy in scanning mode allows to image different contrasts from the sample, by probing not only absorption and phase contrast of the sample but for example a full X-ray fluorescence spectrum or a 2D scattering pattern. Small- and wide-angle X-ray scattering (SAXS/WAXS) imaging is in particular valuable for heterogeneous samples, in which structural elements in the nano- or Ångström-scale change over macroscopic length scales, thus several millimeters or centimeters.[1] The scattering patterns provide statistical information in each scan point, making this method complementary to high-resolution imaging techniques. The information extracted from each scattering pattern can be used to create images with different contrast, such as density of nano-scale features. On 2D detectors the anisotropy of SAXS pattern and texture of XRD can be detected. To resolve this orientation information in extended three-dimensional samples different tensor tomography algorithms have been developed. [2,3]. Extension of the technique to include WAXS data has been demonstrated for cases where the diffraction pattern still shows smooth texture variations from small nanocrystals. [4] New developments also allow the reconstruction of more complicated texture.[3,5,6] Since WAXS-TT does not rely on identification and indexing of individual Bragg-peaks, as the case for 3D-XRD techniques [7], it is very well suited for crystals which are too deformed or too small to yield isolated diffraction spots, as often the case for biominerals. Different application examples will be shown highlighting recent advances of the technique.
References:1] Fratzl, P., Jakob, H. F., Rinnerthaler, S., Roschger, P. & Klaushofer, K. (1997).J. Appl. Cryst. 30, 765–769 [2] Liebi, M., Georgiadis,M., Menzel,A., Schneider,P., Kohlbrecher,J., Bunk,O., Guizar-Sicairos, M (2015), Nature, 527, 349-352,[3] Nielsen, L.C., Erhart P., Guizar-Sicairos, M., Liebi, M. (2023), Acta Cryst A, 79, 515-526[4] Grünewald, T.A., Liebi, M., Wittig, N.K. , Johannes, A. Sikjaer, T., Rejnmark, L., Gao, Z., Rosenthal, M, Guizar-Sicairos, M., Birkedal, H. and Burghammer, M. (2020). Science Advances, 6[5] M. Carlsen, C. Appel, W. Hearn, M. Olsson, A. Menzel and M. Liebi (2024). J. Appl. Cryst. 57, 986-1000[6] Carlsen, M., Malamud, F., Modregger, P., Wildeis, A., Hartmann, M., Brandt, R., Menzel A. and Liebi, M.. (2025). J. Appl. Cryst. 58, 484–494 [7] Poulsen, H. (2004). Three-Dimensional X-ray Diffraction Microscopy. Springer Berlin, Heidelberg.