PISA – Liquid Phase-(Scanning) Transmission Electron Microscopy (LP-(S)TEM)

Liquid Phase-(Scanning) Transmission Electron Microscopy (LP-(S)TEM) allows in situ observations of the dynamic behaviour of materials in liquids, with both high spatial resolution and temporal resolution. In LP-(S)TEM, the liquid cell is mounted at the tip of a specific TEM sample holder, wherein the sample and solvent are placed in-between two electron-transparent windows. Optimal spatial resolution is obtained by minimizing the liquid thickness surrounding the sample, which is achievable by choosing suitable liquid cell spacers. In a liquid cell, the sample is analyzed by (S)TEM in its native state, hence solid/liquid interface is preserved. Nevertheless, incident electron beam irradiation in the liquid phase induces several artifacts that must be accounted for, such as changes in pH, temperature, and chemistry (radiolysis processes occur in the presence of water). To date, this (in situ) technique has been extensively exploited to visualize the formation processes of inorganic nanostructures and biological materials. The GeoForschungsZentrum (GFZ) has its own LP-(S)TEM facility (Protochips Poseidon model), the only one in Germany in a geosciences research unit, which is supported by a full-time postdoctoral researcher.