Improvement of a new scanning electron microscopy method
The researchers from the Department of Polymer Morphology with their colleagues from the Institute of Scientific Instruments CAS improved their own new method of scanning electron microscopy.
Electron diffraction is performed in transmission electron microscopes (TEM) routinely, while in the scanning electron microscopes (SEM) the classical electron diffraction has not been available until recently. “Our previous work, published in Nanomaterials, showed that modern scanning electron microscopes equipped with modern pixelated STEM detectors can be employed in obtaining powder electron diffraction patterns from nanocrystalline samples,” says Miroslav Slouf, head of Polymer Morphology department. The new method was called 4D-STEM/PNBD. The key component of the method is a freeware program package named STEMDIFF. “Our latest work, published very recently in Materials, describes substantial improvement of the method, which is now much easier to use, even for common SEM user without special crystallographic knowledge,” describes Miroslav Slouf.
The method was improved in three important aspects. Firstly, the researchers from IMC and ISI demonstrated, how to set experimental conditions during collection of 4D-STEM datasets easily and efficiently (the 4D datasets are 2D arrays of 2D nanobeam diffraction patterns). Secondly, they incorporated so-called 2D-PSF deconvolution into the STEMDIFF package (the deconvolution improves the resolution of the final diffraction pattern substantially because it minimizes the effect of the primary electron beam spread). Finally, they completely upgraded the whole STEMDIFF package so that it was both easier to install and easier to use (the current version of STEMDIFF is a standard Python package available at the official repository pypi.org, which contains complete documentation and installation instructions).
Support from Center of Excellence and National Center of Competence projects
“How often can you develop a new method in the field of electron microscopy? Once in a lifetime or maybe never,” speculates Miroslav Slouf. “We managed to succeed thanks to long-lasting, smooth and fruitful collaboration between our Department of Polymer Morphology and the laboratory of Dr. Vladislav Krzyzanek at the Institute of Scientific Instruments.” The collaboration has been supported by two big grant projects (Center of Excellence and National Center of Competence). The important partners in both projects are also Czech electron microscope manufacturers. “At the very beginning, the development of electron diffraction techniques started mostly due to collaborations within our Institute, namely with the Department of Polymer Particles that is led by Dr. Horak, for which we analyzed inorganic nanocrystals that were filled into polymer microspheres,” adds Miroslav Slouf.