Physical Chemistry Seminar: Elucidation of Catalytic Reactions and Organic Crystallization Processes Through Ex-Situ and In-Situ High-Resolution TEM Investigations

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Abstract:

Transmission electron microscopy (TEM) has entered a transformative era, yet the field still operates within a fragmented landscape where techniques are often deployed in isolation and electron-dose budgets are treated as constraints rather than design parameters. This presentation details the development of integrated, dose-aware ex-situ and in-situ platforms designed to redefine the methodology for investigating sensitive materials by coordinating multiple modalities, including open and closed gas-cell TEM, 4D-STEM, and low-dose focal-series reconstruction (LD-FSR). It will provide an overview of the possibility of tailoring a framework that preserves the chemistry governing material reactivity and its native state during high-resolution imaging.

The first part of this talk focuses on fundamental work in a state-of-the-art environmental TEM (ETEM) for catalytic systems under realistic conditions. I will present a method to inspect the information limit at a pressure of 1 mbar of gas (ca. seven orders of magnitude more than for a standard TEM). Later, our development of a quantitative real-space TEM method called LD-FSR will be discussed, showing how the technique can be used for near-atomic-resolution imaging and real-space crystallography of organic materials, overcoming the size limitations of X-ray diffraction. Furthermore, a demonstration of the technique while using the ETEM will be presented, including the achievement of 50 pm resolution under gas exposure with monochromated Nelsonian illumination. This capability facilitated the direct observation of sub-angstrom interactions between gas molecules and gold nanoparticle surfaces, revealing distinct atomic column broadening that indicates partial gas activation. In the last part of the talk, a short introduction to 4D-STEM will be presented alongside results of its use while complementing other imaging techniques, specifically for organic crystalline polymers.
 

Seminar Organizer: Prof. Yuval Ebenstein