Experimental set up for in situ transmission electron microscopy observations of chemical processes.

Recently, the applications of transmission electron microscopy (TEM) related techniques have extended from ex situ nanoscale characterization of structure and chemistry of products to dynamic measurements of nanostructures during reaction processes. Commercially available modified TEM specimen holders and TEM columns are being routinely employed to follow the structural and chemical changes at elevated temperatures and even under controlled atmosphere. Experiments performed under these rigorous conditions require careful considerations to avoid undesirable effects from the gas impurities or contaminations from TEM grids and/or holders. The reactivity of sample, grid, holder, TEM components, and gaseous environments must be evaluated for each reaction process. This tutorial is aimed to outline some of the important factors that should be considered for experimental set up used for in situ observations to ensure the results are comparable to the ones obtained during ex situ experiments under identical conditions.