Dr. Maureen Lagos

His group also develops novel methodologies for nanoscale material characterization (e.g. thermometry). Besides his interest in phonons and electronic properties of nanomaterials using EELS, he has worked on temporal aspects of the inelastic electron scattering associated with collective excitations, quantum electronic transport, and mechanical elongation of nanostructures using in-situ TEM. He obtained his PhD in Physics from The State University of Campinas. He is Canada Research Chair in Imaging and Spectroscopy of Advanced Nanomaterials, and he currently serves as Associate Scientific Director of the Canadian Centre for Electron Microscopy.

Spectroscopy and Imaging of Phonons in the Electron Microscope

Joaquin Reyes-Gonzalez¹, Ka Y. Lee¹, Philip E. Batson², Peter Rez³, Maureen J. Lagos^1,4

¹ Department of Materials Science and Engineering, McMaster University, Hamilton, Canada.

² Department of Physics, Rutgers University, New Jersey, USA.

⁴ Department of Physics, Arizona State University, Graz, Austria.

⁵ Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Canada.

^*mjlagos@mcmaster.ca

Scanning transmission electron microscopes (STEM) equipped with high energy resolution monochromators permits the realization of phonon spectroscopy studies in materials using atom-wide electron probes. Instrumental developments are still in progress and energy resolutions of 3.7 meV at 60 kV were recently obtained. As it is usual the case, phonon spectroscopy experiments are complex and data interpretation presents enormous challenges. But despite these barriers the electron microscopy community has made progress in obtaining a much deeper understanding of the inelastic electron scattering by phonons in nanoscale materials. This is permitting us to uncover new and exotic properties of materials. In this presentation, we will describe this progress by highlighting results in areas of nanophotonics and nanoscale heat transfer: (i) imaging surface and bulk phonon modes in a single nanoparticle, (ii) uncovering plasmon-phonon coupling in infrared antennas, (iii) mapping hyperbolic phonon polaritons in twisted low symmetry crystals, (iv) the development of a thermometry methodology to measure local temperature with nanoscale resolution, and (v) probing heat transfer channels across nanogaps. Our results provide progress towards understanding the role of surface and bulk phonons in physical process involving light-matter interaction and nanoscale heat transfer.