Momentum Resolved Excitation Transmission Electron Microscope
A major mission of condensed-matter physics is to understand material properties via the knowledge of the energy vs. momentum dispersion and lifetime of fundamental excitations. Unfortunately, the available techniques cannot be applied to emerging nanostructured materials. Inelastic x-ray scattering or electron energy loss spectroscopy (EELS) in reflection lacks the spatial resolution and EELS in transmission electron microscopy (TEM) lacks the needed energy and momentum resolution. In MORE-TEM, an innovative nano-spectrometer to measure momentum-dependent excitations with the unprecedented energy resolution (dE < 5 meV) should be developed. In addition, a temperature control down to liquid He, a simultaneously lateral resolution of tens of nm on samples as thin as an atomic monolayer are further goals of this project. In STEM mode an ultra-high spatial resolution should be achieved too.
This breakthrough should be realized by bringing together four groups with complementary skills ranging from TEM and electron optics to experimental/theoretical spectroscopy. MoRe-TEM opens the so-far unexplored possibility to investigate dispersion and lifetime of phonons, plasmons and excitons in hierarchical quantum matter including bio- and organic molecules, 1D nanotubes, 2D materials and van der Waals heterostructures, and nanocrystals of minerals and soft matter. Mapping out the energy and momentum landscape of primary excitations will make it possible to gain control on quantum phases, like charge-density waves and superconductivity, to engineer new materials for opto- and electronic nanodevices and for organic electronics, and to model the physical properties of natural geological systems. This will hugely impact a broad range of applications in the fields of solid-state physics, chemistry, biology, geology and engineering. MoRe-TEM not only implements features of a large synchrotron facility on a cheaper table-top instrument, but it also pushes the momentum-resolved spectroscopy to the realm of the nanoscale, providing thus a fundamentally new and unique infrastructure for the characterization of materials.
Tasks of CEOS
For CEOS this project means the development of a new monochromator at ground potential which allows the reduction of the energy width down to the requested energy width dE < 5 meV of the electron beam of a cold field emitter. One of the most important goals will be to optimize the electron gun in combination with the monochromator to achieve a beam current which allows the acquisition of EELS data with the requested precision. Besides the monochromator an ultra-high energy resolution spectrometer will be a prerequisite too.
The Corresponding Principal Investigator #1:
Prof. Thomas Pichler, University of Vienna, Faculty of Physics
Principal Investigator #2:
Prof. Francesco Mauri, Università di Roma La Sapienza, Faculty of Physics
Principal Investigator #3:
Prof. Kazu Suenaga, AIST, Osaka, Japan
Principal Investigator #4:
Prof. Maximilian Haider, [CEOS GmbH](), Heidelberg
Figures by courtesy of K. Suenaga. The full paper was published by:
R. Senga, P. Barone, S. Moryshita, F. Mauri and T.Pichler, Nature Vol.573 (2019) 247 – 250, https://doi.org/10.1038/s41586-019-1477-8