Application of Ionic Liquid as a Liquid Conductive Material to Electron Microscopy

Abstract

Ionic liquids are salts in liquid state even at room temperature. Since they have extremely low vapor pressure, they are not vaporized even in vacuum conditions. Focusing on this fact, the author has discovered that ionic liquids can be observed by scanning electron microscope without any charging, implying that ionic liquids behave as conducting materials for electron scope observations. Then, the author is now developing new electron scope techniques by using ionic liquids as liquid conductive materials. The use of ionic liquids is very effective for the SEM observation of soft bio-samples whose surfaces are very complex and are changed by drying. In case of the TEM observation, forming liquid films in the holes of a TEM grid and putting samples in the liquid films enable the observation of samples without any deformation. When chemical reactions are induced in an ionic liquid that is placed in a SEM chamber, in situ SEM observation and in situ EDX measurement of the reactions are possible. Some examples of electrochemical reactions such as metal deposition, metal dissolution, and electrochemical actuator reactions are introduced in this article.