Search for: All records

Abstract Based on historical developments and the current state of the art in gas-phase transmission electron microscopy (GP-TEM), we provide a perspective covering exciting new technologies and methodologies of relevance for chemical and surface sciences. Considering thermal and photochemical reaction environments, we emphasize the benefit of implementing gas cells, quantitative TEM approaches using sensitive detection for structured electron illumination (in space and time) and data denoising, optical excitation, and data mining using autonomous machine learning techniques. These emerging advances open new ways to accelerate discoveries in chemical and surface sciences. Graphical abstract 

Surface strain often controls properties of materials including charge transport and chemical reactivity. Localized surface strain is measured with atomic resolution on (111) ceria nanoparticle surfaces using environmental transmission electron microscopy under different redox conditions. Density functional theory (DFT) coupled with TEM image simulations have been used to interpret the experimental data. Oxygen vacancy creation/annihilation processes introduce strain at the surface and near surface regions of the cation sublattice. Both static and fluxional strainmaps are generated from high resolution images recorded under varying reducing conditions. While fluxional strain is highest at locations associated with unstable vacancy sites, highly inhomogeneous static strain fields comprising of alternating tensile/compressing strain is seen at the surface and subsurfaces linked to the presence of stable oxygen vacancies. Interestingly, both stable and unstable oxygen vacancies are found within a few atomic spacings of each other on the same surface. The static strain pattern depends on the ambient environment inside the TEM.