Pumping, Measuring and Modeling Atomic Vibrations in the Electron Microscope – PuMMAVi

The spectral resolution of electron energy loss spectroscopy in the transmission electron microscope
has recently reached 5 meV, opening novel possibilities for probing vibrations in materials with
unprecedented spatial resolution. Combining the development of in-situ THz injection with new
theoretical approaches based on first-principles calculations, the PuMMAVi project is designed to
better understand vibrational phenomena in emerging nanomaterials down to the atomic scale.
In particular, localised phonons in GaN and AlN-based nanowires arising from the presence of
surfaces, interfaces, structural defects and impurities will be measured and modelled to reach a
deep understanding of phonon-dominated thermal transport in quasi one-dimensional systems
with direct implications for heat dissipation in nanowire-based light emitting diodes and the role
of defects in this process.