ACMIN Seminar: „X-ray microscopy and ptychography of biomelecules and nanoparticles”
It is our pleasure to invite you to attend the ACMiN Seminar which will be held on Thursday, September 29 at 2.00 p.m. in the ACMiN auditorium no.: 1.02A, on the second floor, bldg. D-16 (Kawiory Street 30).
The lecture entitled: „X-ray microscopy and ptychography of biomelecules and nanoparticles” will be given by dr Karolina Stachnik (CHyN, Hamburg University, Germany).
X-ray ptychography is a robust and promising scanning coherent-diffraction imaging technique, yielding quantitative optical density contrast at dose-limited spatial resolutions beyond the fabrication limits of X-ray optics. Its scanning nature allows for simultaneous X-ray fluorescence (XRF) mapping, that enables artefact-free correlations of trace elements with highly resolved specimen’s morphology. Moreover, ptychography can also be combined with computed tomography, yielding quantitative 3D electron-density maps of extended specimens down to sub-100-nm spatial resolutions. By using high-quality coherent X-ray beams, low-background setups, and optimized scanning routines, multimodal scanning X-ray microscopy aspires to an excellent tool for high-resolution structural investigations of weakly absorbing objects in 3D.
In the first part of this talk, I will present the application of ptychography with concurrent XRF mapping at beamline P11 at the low-emittance synchrotron storage ring PETRA III, DESY. Here, a scanning X-ray microscope was developed, featuring a Fresnel zone plate as an illumination-forming optic, high-throughput scanning unit, and a high-framerate detector. The correlative method was used to image a population of macrophages treated with iron-oxide nanocontainers for tuberculosis drugs. The concurrent imaging techniques were further applied to study the mineralization of a human bone matrix. In the second stage, the X-ray microscope was upgraded with a rotation stage permitting ultrafast tomographic measurements. I will demonstrate its operation with ptychographic tomograms of representative specimens.
In the second part of this talk, I will present the application of X-ray ptychography for high-resolution in-situ imaging of chemical systems. Understanding the nucleation and growth mechanisms involved in the synthesis of nanomaterials is a key factor in determining their performance and functionality. In many cases, these processes are still not well understood, in particular due to the difficulty of observing them in-situ or operando. In this case, scanning hard X-ray microscopy offers the potential for in-situ nanoimaging of complex chemical systems under relevant environmental conditions. Here, I will show results of our joint activities within the XStereoVision Röntgen-Ånström Cluster German-Swedish project. We utilize the PtyNAMi X-ray microscope at beamline P06 at PETRA III, DESY, to visualize the transformation of Cu2O cubes into Au nanocages by galvanic replacement. We will show how to determine the amount of radiation damage making use of the quantitative phase images. Finally, we will discuss potential experimental solutions to these irradiation effects.