Among various in-situ techniques in catalyst chemistry, environmental transmission electron microscopy (ETEM) recently advanced at the atomic scale. The technique provides us mostly with static structural data of solid catalysts in reaction environments. Given the recent advancement of a TEM image detector such as a CMOS-based TEM camera, an apparatus for controlling an electron beam [1] and a photocathode, the technique has started progressing to reveal the atomic dynamics that are correlated with catalysis. In this presentation, we show some recent challenges of time resolved analyses using fast CMOS based cameras by atomic scale and microsecond resolution ETEM on the oxidation and reductions processes on the surfaces of Pd, Pt, Au and related materials. Though a chemical reaction is an extremely fast electronic phenomenon, the previous studies has clarified the atomic dynamics occurring on the surfaces of active metals, for instance surface reconstruction, crystallographic morphology changes and others that are associated with catalysis. These atomic dynamics are much slower phenomena and thus can be observable by the technique.<br/><br/>In addition, to reveal catalytic processes, it is important to understand the influence of the imaging and measurement processes on a specimen. Especially, to derive clearly the intrinsic natures of a specimen in a reaction environment by atomic scale and microsecond resolution ETEM, it is still indispensable to consider the influence of electron beam: heating and ionization of a specimen, and knock-on of atoms in a specimen. The hardware and software [1] will be crucially useful to control and/or diminish electron irradiation damage in an extremely fragile specimen with temporal resolution better than 1ms, especially combined with a fast CMOS camera. Furthermore, we focus on secondary electrons of low energy that are emitted from a specimen under the irradiation of high energy electrons for ETEM observation. Secondary electrons may cause various effects on ETEM analyses to some extent and occasionally useful to fabricate an artificial nanostructure. We demonstrate that the combination of the primary electrons of high energy, the secondary electrons of low energy and effective gases can be utilized for cutting carbon nanomaterials with nanometer accuracy [2] and also related applications.<br/><br/>

Time resolved and atomic resolution environmental TEM of metal surface in gas environment

256th National Meeting (2018)

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