Soft matter research makes extensive use of scanning/transmission electron microscopy (S/TEM) to probe micro- and nano-structural morphology and to map chemical information. Materials consisting of carbon and other light elements are relatively weak electron scatterers - this leads to a number of unique and interesting possibilities, especially as new technology and techniques become available.
3D S/TEM – thick specimens
One advantage of the physical and chemical nature of soft matter is that high energy primary electrons can pass through a large volume of material, enabling examination of comparatively thick specimens, relative to more dense materials. If the sample is systematically tilted in the S/TEM, a series of projections can be collected and tomographic reconstruction can be used to provide a 3D visualization of the bulk structure. A new technique, low convergence angle STEM, has been applied to imaging and 3D volume analysis of specimens extending over several microns in thickness yet with local resolution in all three dimensions of a few nanometers. This gives access to critical length scales of interest in functional materials and devices, allowing characterization of porosity in bulk materials, identification of nano-networks and mapping of phase separation in polymer systems.
Low voltage S/TEM – aberration-corrected Titan 80-300
The low scattering power of soft materials can give rise to low contrast between different components, but there are numerous ways to enhance this contrast, including staining of the different phases or using low primary electron accelerating voltages. The advent of the Titan 80-300, equipped with a spherical aberration Cs corrector and a voltage range between 80 and 300 kV, means that voltages can comfortably be reduced to 80 kV and still enable atomic resolution imaging and analysis - without staining. Furthermore, many soft materials rapidly undergo radiation damage at higher voltages, because of the knock-on of atoms, and so for some soft materials systems, 80 kV imaging offers a more gentle alternative. High tension flexibility means that the Titan 80-300 can be tuned to provide optimal results for the widest range of materials, whether soft, hard or somewhere in between.
Applications for Materials Science: