Recent developments in dynamic transmission electron microscopy

One of the current major driving forces behind instrument development in transmission electron microscopy (TEM) is the ability to observe materials processes as they occur in situ within the microscope. For many processes, such as nucleation and growth, phase transformations and mechanical response under extreme conditions, the beam current in even the most advanced field emission TEM is insufficient to acquire images with the temporal resolution (∼1 μs to 1 ns) needed to observe the fundamental interactions taking place. The dynamic transmission electron microscope (DTEM) avoids this problem by using a short pulse laser to create an electron pulse of the required duration through photoemission which contains enough electrons to form a complete high resolution image. The current state-of-the-art in high time resolution electron microscopy in this paper describes the development of the electron optics and detection schemes necessary to fully utilize these electron pulses for materials science. In addition, developments for future instrumentation and the experiments that are expected to be realized shortly will also be discussed.

► In situ TEM provides unique insights into the transient structures that occur during materials synthesis and processing.
► Dynamic transmission electron microscopy (DTEM) allows in situ experiments to be performed with high temporal resolution.
► Modifications to the microscope column to accommodate short pulses help to maintain the spatial resolution at ∼5 nm.
► Future improvements should extend the combined spatial and temporal resolution further.