High-energy electron diffraction is a sensitive probe of the crystal lattice. In an ultrafast pump-probe scheme, it is sensitive to variations in the crystal lattice, such as structural phase transitions and the evolution of laser-induced phonon populations.

The technique probes reciprocal space (i.e. momentum space), and information is extracted from Bragg reflections that occur due to elastic scattering of the probe electrons.

Additional information is obtained by recording the inelastically scattered electrons. These are typically scattered off of phonons, and so provide a momentum-resolved image of the phonon population.

High-energy electron diffraction is complementary to Ultrafast X-ray diffraction, but has the advantage of a very large Ewald sphere provided by the de Broglie wavelength of the electrons. This allows probing large sections of reciprocal space at once.

We conduct these experiments in collaboration with the Structural & Electronic Surface Dynamics Group of Ralph Ernstorfer.