High-Resolution TEM Imaging: Phase Contrast and Simulations

This lecture provides an in-depth exploration of high-resolution transmission electron microscopy (HRTEM) imaging, focusing on phase contrast imaging techniques. The instructor begins by explaining the fundamental principles of HRTEM, emphasizing that the images produced are interference patterns resulting from the interaction of multiple electron beams with the sample. The discussion includes the significance of lattice fringes and how they relate to atomic structures, highlighting the complexities introduced by lens aberrations and sample thickness. The lecture also covers the importance of simulations in interpreting HRTEM images, particularly through the weak phase object approximation and multi-slice calculations. Various examples are presented, including imaging of gallium arsenide nanowires and titanium dioxide layers, illustrating how defocus and thickness affect image contrast. The instructor emphasizes the advancements brought by aberration correction in modern microscopes, which enhance resolution and allow for real-time imaging of atomic movements. The session concludes with a discussion on the future of HRTEM imaging, including the potential integration of AI in image analysis and interpretation.