Quantitative low energy 4D-STEM imaging of beam sensitive samples

The project focuses on the development of quantitative imaging methods for scanning electron microscopy (SEM), which will be based on the use of a 2D pixel detector in the transmission mode. The thickness measurement technique recently developed for the annular STEM detector will be extended. At the same time, diffractive techniques (such as ptychography) will be implemented, which thanks to the possibility to provide phase contrast, will allow to show very fine details. Although diffractive techniques are already implemented in classical STEM systems, we will focus on the lower electron energies used in the SEMs. Emphasis is also placed on the application of these methods to samples that are sensitive to electron beam irradiation (most biological and polymer samples). Therefore, not only 4D-data acquisition techniques with the least possible sample damage will be sought, but also the inclusion of cryogenic techniques that can suppress radiation damage. The project includes the development of experimental apparatus, dedicated software and methodology to test selected samples.