Microstructured liquids (‘complex fluids’, ‘condensed soft matter’) are liquids with density gradients over distances of nanometers to micrometers. Cryogenic temperatures are essential for making specimens of these systems compatible with the electron microscope. The general goal of our work has been understanding supra-molecular microstructure (i.e., microstructure on the size-scale of molecular clusters and bigger) of liquid and semi-liquid systems, and its relation to molecular composition, on one hand, and the macroscopic properties, on the other hand. Transmission electron microscopy (TEM) is one of the most useful techniques in the study of microstructured fluid systems. The technique provides high resolution direct images, thus the interpretation of the data is not model-dependent, although it does require full understanding of the mechanism of specimen preparation, image formation and the physics of interactions between the electron beam and the specimen. The technique involves ultra-fast cooling of thin liquid films, quenched from a controlled environment, to vitrify the samples, that are examined in the TEM at cryogenic temperatures. The basics of the technique will be explained.

Digital imaging cryo-TEM has become an important extension of transmission electron microscopy at cryogenic temperatures of soft matter. I plan to describe the advantages of the technique and demonstrate its use in the study of micellar systems. We have shown how details that had been impossible or difficult to image, can be easily observed by this novel technique. For example, micelles were in past imaged as dots or one-dimensional lines. Now we can show fluctuations in width, inner structure of branching zones, and end-caps of threadlike micelles. It is emphasized that the introduction of digital imaging to cryo-TEM is not merely a small technical improvement, but does promise to expand the capabilities of TEM of complex fluids in a most significant way.