Electron Holography on Beam Sensitive Materials: Organic Polymers and Mesoporous Silica

For the investigation of weak phase objects such as polymers by means of conventional electron microscopy, the objects have to be stained prior to imaging or imaged under strong defocus to find a sufficient contrast in the image. However, these techniques bear the risk of artifacts, e.g., chemical staining and the appearance of Fresnel diffraction phenomena occurring during defocus. These artifacts do not appear with holography. Therefore, holograms of ultrathin sections (50−70 nm) of organic block copolymer were recorded, and the corresponding phase images were reconstructed. In this way, typical structures such as lamellae and onion patterns could be imaged without any staining. In addition, we successfully recorded holograms of mesoporous silica molecular sieve MCM-41 which show the hexagonal arrangement of uniformly sized porosities without using defocus. Holography has been demonstrated as a feasible tool to image beam sensitive and weak phase objects without artifacts.