Ultrafast Electron Scattering at Low Temperatures

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There is currently an enormous, world-wide effort directed at the development and application of new experimental methods that make it possible to directly ‘watch' the time-evolving structure of matter. These approaches combine state-of-the-art femtosecond lasers (see Nobel Prize in Physics, 2018) and sources of either ultrashort Xray or electron pulses to acquire time-resolved diffraction/scattering patterns and images. At the highest time-resolution achievable in these instruments, atomic motion is essentially frozen during an observation and one can completely follow the fundamental dynamics to produce a "molecular movie"; the experimental equivalent of a molecular dynamics simulation. It is possible to watch chemical bonds break/form and directly determine transition-state structures for even complex reactions, to follow phase transition dynamics uncovering the deep connections between the structure and properties of materials, and even to obtain an atomic-level understanding of protein function with these approaches. ***This proposal is focused on the further development of the World's most powerful ultrafast electron scattering instrument, designed, built and operating at McGill University. We are requesting equipment that builds on previous successes and enables ultrafast electron scattering at cryogenic temperatures. This new capability will open up an enormous new 'scientific space' to be explored. With the requested equipment, we expect to be able to shed new light on materials phenomena as diverse as superconductivity, charge density waves, thermoelectricity, photovoltaicity and carrier mobility in semiconductors and metals. We will be in a position to investigate the complex interplay between strong, multi-orbital electronic correlations, structural distortions, charge and orbital order across a range of strongly correlated material where this physics determines properties (transition metal oxides, pyrochlore oxides, manganites and cuprates), and there is a possibility of discovering new photoinduced phases and avenues for optical control of complex materials, a topic at the forefront of materials research.