Recent developments in time-resolved diffraction techniques -- both x-ray and electron -- have made it possible to observe matter at unprecedented spatio-temporal resolution. These developments have been enabled by so-called 'ultrafast' xray and electron sources, which are capable of taking (essentially) instantaneous snapshots of the atomic structure of matter. Studies that make use of these sources have begun to open up a new window on the time-evolving atomic configuration of molecules and solids during structural transformations, since by piecing together a sequence of such snapshots we can obtain an atomic resolution "movie" of the process.
My talk will focus on ultrafast electron diffraction (UED), and will provide a very accessible introduction to this field. I will describe the goals and methods of UED as well as the technical challenges associated with the development of ultrafast electron sources. As part of this overview I will demonstrate that we have recently been able to improve our diffractometer performance by several orders of magnitude by borrowing some technology from the particle accelerator community.
Several experiments that highlight the power of ultrafast diffraction for studying structural dynamics at (or near) atomic resolution will then be described. Moving beyond diffraction experiments, ultrafast transmission electron microscopy will also be discussed (time permitting).