Electron-Induced Radiolysis Chemistry in Fluid Cell Electron Microscopy: Application on the Reactivity of Aluminum Nanocubes

Leveraging the high energy electrons as probe for the atomic landscape of materials, the importance of understanding radiolysis chemistry in the field of transmission electron microscopy (TEM) is exceptionally important. Reactive chemical species generated from electron-material interactions diffuse throughout the sample and may induce "artifact" reactions with the specimen of interest. However, in other aspects, this radiolysis can be utilized to intentionally trigger chemical reactions related to the nucleation and growth of colloidal nanoparticles, as well as chemical etching under a priori conditions in fluid condition. Therefore, systematic research and new theories are required to help researchers gain a deeper understanding of these electron-materials interactions either to mitigate damage or rationally use radical chemistry especially in the environmental TEM (E-TEM). Radiolysis in open-cell gas phase TEM (GPTEM) under reduced pressures is usually disregarded considering the low density of molecules and high diffusivity. However, for emerging closed-cell GPTEM, which usually involves the usage of higher pressures, less is known. Here, we utilize an ultrathin (UT) silicon nitride gas cell to investigate and quantify the effects of electron dosage on the oxidation behavior of 100-faceted aluminum (Al) nanocubes under various conditions. In addition, we develop a generalized computational code to elucidate radiolysis chemistry in varying media with consideration of the diffusion dynamics, while rationalizing the experimental observations. Based on these theoretical electron-fluid interaction models, we propose guidelines to control the radical species of the closed-cell in situ nanoreactors, paving the way to the nanoscale control of chemical reactions in E-TEM.