Resolution and Downtime Improvements for in situ Liquid Cell Transmission Electron Microscopy

Abstract

The goal of this thesis is to develop a vapor delivery system and a water expulsion system to enhance the in situ study of materials in a closed liquid cell under a scanning/transmission electron microscope. The visualization of chemical reactions in solution via liquid cell transmission electron microscopy (LC-TEM) has gained traction in the past few decades, but is still very challenge due to the complexity of operation. The present liquid cell techniques are advantageous in the study of microstructural evolution of large particles of heavy metals and heavy compounds, but not for small metal particles and light compounds due to the thick layer of liquid between the two transparent windows in the liquid cell (a thickness of at least 2um). We have found that it is hard to distinguish the small particles of calcium phosphate in a liquid cell under a scanning/transmission electron microscope. To solve this problem, we develop a vapor delivery system which enables the study of chemical reactions of light compounds in vapor conditions and a water expulsion system which facilitates the quick drying of the tubes and liquid cell. After completing the mechanical design of the vapor delivery and water expulsion systems, the focus will be on testing these systems and performing experiments. The main experiment performed is the decay of bovine enamel using citric acid vapor. The process will be imaged in situ to view the process and results. Lastly, the experimental image series are analyzed to confirm enamel decay, and the efficacy of the vapor delivery system and water expulsion system are evaluated.