Karl Franzens University Graz
Graz University of Technology
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Karl Franzens University Graz | Graz University of Technology | |
Advances in Automated Electron Diffraction Tomography Transmission electron microscopy is an established method for structural characterization of nano crystalline material by imaging, diffraction and elemental analysis. High resolution TEM imaging demands high electron dose on the sample, often problematic for frameworked and hydrated inorganic materials. By using electron diffraction a significantly lower electron dose is applied. Traditionally, electron diffraction data is collected by orienting low index zones which delivers a limited number of accessible reflections and enhances dynamical effects. Automated electron Diffraction Tomography (ADT), is the first method using non-oriented diffraction patterns. After reconstruction of the collected data in a 3D reciprocal space, cell parameters, space group and intensity data can be taken. The strong reduction of dynamical effects in non-oriented zones allows a standard kinematic approach usually delivering ab-initio a complete structural model. It was possible to solve structures from single nanocrystals down to 30 nm. Using ADT it is possible to access complex inorganics structures as well as highly beam-sensitive organics like pharmaceuticals. Remarkably, large cell structures of porous minerals, zeolites and beam-sensitive metal-organic frameworks have been solved in the last years by direct methods. |