Effect of electron beam irradiation in gas atmosphere during ETEM

Transmission electron microscopy (TEM) is used to observe the atomic structures of materials. Environmental TEM (ETEM) is a method wherein a gas can be evaluated and it has been used to observe the dynamic reaction between materials and gases at the atomic level. An electron beam (EB), which has a sufficiently high energy (exceeding a few tens of kilovolts), can be used to ionize gas molecules. Subsequently, the ionized molecules might react with the materials during ETEM. Therefore, the current generated by the ions and electrons were measured to verify the presence of ions generated due to the ionization of the N₂ gas atmosphere during EB irradiation in ETEM. The electron energy loss spectra (EELS) were acquired from the N₂ gas atmosphere to estimate the types of ions generated. The results demonstrated that ions and electrons were generated in the N₂ atmosphere during ETEM and EB irradiation. Moreover, the EELS analysis indicated that the generated ion was N₂⁺. The material observation conducted using gas ETEM can detect the reaction between gases, ions, and materials.