Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session S13: Industrial and Applied Transmission Electron MicroscopyIndustry Invited Live Streamed
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Sponsoring Units: FIAP Chair: Todd Brintlinger, United States Naval Research Laboratory Room: McCormick Place W-183A |
Thursday, March 17, 2022 8:00AM - 8:36AM |
S13.00001: Probing atomic reconstruction at 2D interfaces via scanning transmission electron microscopy Invited Speaker: Pinshane Y Huang Scanning transmission electron microscopy (STEM) provides uniquely powerful tools to study the interfacial structure and interactions of 2D materials up to atomic precision. In my talk, I will discuss how we create and utilize 2D multilayer stacks to create nanoscale laboratories for studying the atomic structure, structural transformations, and properties of 2D interfaces inside the STEM. For example, we utilize graphene encapsulation in combination with a MEMS-based heating holder to conduct in-situ studies of solid-solid phase transformations and restructuring in 2D transition metal dichalcogenides (TMDCs). We use these structures to directly visualize phenomena such as the layer-by-layer phase transformation of MoTe2 and the lattice reconstruction of 2D moirés. |
Thursday, March 17, 2022 8:36AM - 9:12AM |
S13.00002: Exploiting automatic image processing and in-situ transmission electron microscopy to understand the stability of supported nanoparticles Invited Speaker: Eric Stach The activity and lifetime of heterogeneous catalysts are linked with their structural stability in reactive environments. Atmospheric pressure electron microscopy is used to understand how a model catalyst – Pt/Pd nanoparticles supported on Al2O3 – responds to reduction and oxidation. Significant metal vaporization and diffusion were observed at temperatures above 600 °C, in oxygen and air. This behavior implies that material transport through the vapor during typical catalyst aging processes can play a significant role in catalyst evolution. We developed and exploited data analysis tools to track the temporal evolution of Au nanoparticles deposited on SiN as a model system to understand this process. We describe how a systematic investigation of dataset preparation, neural network architecture, and accuracy evaluation lead to a tool for determining the size and shape of nanoparticles in high pixel resolution TEM images. We use this algorithm to generate data regarding the complexities of nanoparticle coarsening, ripening, and evaporation. We have developed an analytical model that describes this process, showing how local and long-range particle interactions through diffusive transport affect evaporation. The extensive data allows us to determine physically reasonable values for the model parameters, quantify the particle size at which Gibbs-Thompson pressure accelerates the evaporation process, and explore how individual particle interactions deviate from mean field behavior. |
Thursday, March 17, 2022 9:12AM - 9:48AM |
S13.00003: Electron Spectroscopy of Infrared Excitations at the Nanoscale Invited Speaker: Maureen Lagos Plasmon-phonon coupled modes and surface phonon polaritons are key players in strong light-matter interaction and radiative heat transfer, respectively. Probing those excitations using spatially-resolved EELS has unveiled new exotic behavior extending our understanding of properties of infrared excitations at the nanoscale. We will discuss two EELS studies in nanosystems with compelling properties for nanophotonics and heat transfer applications: i) Spectroscopy and imaging of strongly-coupled plasmon-phonon modes in a double infrared antenna. Those hybrid modes are the result from a Rabi splitting as small as 26 meV, with coupling constant of 18 meV, fulfilling strong-coupling conditions. The spatial distribution of those plasmon-phonon modes was imaged providing insights into the local electromagnetic density of states. ii) Spectroscopy of surface phonon polaritons within nanoscale gaps. Gaps with distances ranging between 5 and 150 nm were fabricated to explore different regimes of phonon coupling as a function of temperature. Large variety of modes were probed within the gaps indicating multiple available channels for heat transfer processes. The spatial distribution of scattering across the nanogaps was determined revealing a strong temperature-dependent behavior, which suggest a complex interplay between thermal and vibrational behavior. Our work represents advances in the study of IR excitations sustained in nanostructures. |
Thursday, March 17, 2022 9:48AM - 10:24AM |
S13.00004: Nanoscale Analysis of Phonons, Polaritons, and Molecular Vibrations in Complex Materials Invited Speaker: Jordan Hachtel Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) is a powerful tool that allows for direct nanoscale access to the localization of collective excitations in complex materials. With modern monochromators the energy resolution of EELS can reach down into the mid-infrared regime providing access to infrared quasiparticles such as phonons, phonon-polaritons, and molecular vibrations while retaining an Ångstrom scale probe. This unprecedented combination of spatial and spectral resolution enables a host of new experiments that just a decade ago would’ve been impossible. |
Thursday, March 17, 2022 10:24AM - 11:00AM |
S13.00005: From the Atomic Structure to the Optoelectronic Properties Studies of 1D and 2D Complex Nanostructures via TEM Invited Speaker: Raul Arenal In the last two decades, transmission electron microscopes (TEM) have undergone a large number of improvements allowing very high energy resolutions (few meV) for a close to one angstrom electron beam. These performances offer new possibilities in different TEM fields, in particular these ones concerning the low-energy-loss measurements: studies of the optical, dielectric and electronic properties of materials with unprecedented spatial information. In this contribution, I will present a selection of recent works taking advantage of these new capabilities in a TEM for studying the atomic structure and the opto-electronic properties of different 1D and 2D nanostructures [1-5]. In particular, I will focus on the in-situ thermal reduction of the graphene oxide (GO) [1,2], including the transport measurements carried out during the reduction of this material [2] as well as on the studies of 1D misfit layered nanomaterials [3,4] and the plasmonic response of high-aspect ratio Au nanowires [5]. These works illustrate the rich information that can be obtained via this kind of experiments and their interest for studying such nanomaterials. All these findings improve the knowledge of these complex nanomaterials, which is crucial for the study of their physical properties and its future applications. |
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