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The observation of atomic rearrangements as they occur during phase transformations and chemical reactions has long been the exclusive domain of computer simulations. Advances in the production of ultrafast structural probes over the last twenty years have finally brought such “molecular views” to the experimental ground. The challenge has been the creation of hard X-ray or electron pulses bright and short enough to capture atoms on the fly; namely sub-picosecond (< 10^-12 s) and the shorter the better to avoid motion blur in stroboscopically recorded images. The brightest fourth generation light source on earth (LCLS, Stanford) is now delivering hard X-ray pulses as short as 5 femtoseconds (1 fs = 10^-15 s) with enough photons to attain high-quality single-shot diffraction1. On the other hand, laboratory-based femtosecond electron diffractometers (FEDs) have also emerged as a powerful means to monitor coherent atomic motion². New source concepts are in fact expected to provide multi-electron bursts < 30 fs³. I will give an overview of the field of ultrafast structural dynamics and discuss the current team efforts towards the development of technology for imaging structure and structural dynamical processes with atomic spatiotemporal resolution.

1. SLAC Linac Coherent Light Source. (2016). Available at: https://portal.slac.stanford.edu/sites/lcls_public/Pages/Default.aspx.
2. Sciaini, G. & Miller, R. J. D. Femtosecond electron diffraction: heralding the era of atomically resolved dynamics. Rep. Prog. Phys.74, 096101 (2011).
3. Petruk, A., Pichugin, K. & Sciaini, G. Shaped cathodes for the production of ultra-short multi-electron pulses. Struct. Dyn. 4, 044005 (2017).