Closed Cell Systems for In Situ TEM with Gas Environments Ranging from 0.1 to 5 Bar

The ability to carry out reactions with gas mixtures in a TEM is becoming an increasingly important field of study, known as environmental transmission electron microscopy (ETEM). Different approaches exist to expose the material to a gas while imaging in a TEM: an open system employing differential pumping and a closed system using microelectromechanical systems (MEMS). The latter approach using electron transparent windows in a device holding the specimen and the gas came up during the last decade, enabling a gas pressure of several bars. Here, we present this closed cell approach based on a functional MEMS device known as “nanoreactor” to investigate gas–material interactions inside a TEM. We discuss the design and the development of different kinds of nanoreactors, along with the necessary accessories to carry out drift-stabilized, atomic-resolution environmental TEM studies. Finally, examples showing the applications of the nanoreactor to investigate several gas–liquid–material interactions are presented.