Investigation of Effect of Electron Irradiation on Ionic Liquid Using Electron Holography

Ionic liquid (IL) has various attractive features and attract a great attention as new functional materials for applications. Recently, it has been reported that ILs were applied in scanning electron microscopic (SEM) observation because they do not vaporized even in vacuum condition [1]. Moreover, they can be also used as solvents and supporting films of nanoparticles for transmission electron microscopic (TEM) observation. Technique using ILs is useful for new electron microscopic observation and is expected to be applied widely in various filed. Before utilizing them for electron microscope applications, we need to examine their charging effect under electron irradiation. We employed electron holography [2] to characterize their charging effect. Electron holography is a unique technique to directly observe electromagnetic fields and quantitatively analyze the electrostatic potential distribution with high spatial and phase resolution. In the present study, we investigated the changes of the electrostatic potential around ILs under electron irradiation and its surface state change from liquid to solid.