Development and Design of Desktop Ultrafast Low Voltage Transmission Electron Microscopy & Quantum Electron Microscopy

桌上型超快低壓透射電子顯微鏡和量子電子顯微鏡的開發與設計

Student thesis: Doctoral Thesis

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Award date20 Sep 2021

Abstract

Over the past decade, electron microscopy has become indispensable for studying nanomaterials and life science. In principle, the latest generation aberration-corrected transmission electron microscopes (TEMs) could achieve sub-Å resolution with single-atom sensitivity across the periodic table in both broad beam and focus beam imaging modes, which has opened up unprecedented insight into materials science. However, there are three bottlenecks: radiation damage, static picture, and 2D projection, still waiting to be overcome for soft materials imaging. The most important one is radiation damage since observations at the atomic level with single-atom sensitivity requires an intense electron illumination that generally alters the nanostructure during observation. Good signal/ noise ratio imaging without affection from electron beam that causes damaging the sample is essential for the future development of TEM.

The ultimate idea to eliminate all the radiation damage for soft materials imaging is an interaction-free (no interaction between the electron beam and sample) quantum electron microscope (IF-QEM), which is planned to build based on the principle of the Zeno quantum effect. In this thesis, I take an adventure attempt to explore the possibility of the interaction-free (Quantum) electron microscope, in which case the electron will not interact with the sample if the sample is a perfect absorber. The IF-QEM system is composed of a highly coherent pulsed FEG, a fast deflector to produce pulse source, condenser lenses and objective lens, Cs/ Cc aberration correctors, quantum resonator, including multipole beam splitter and combiner, π-bending magnets, etc. The practical realization of a quantum electron microscope will be built based on a self-designed low voltage (~15 keV) scanning transmission electron microscope. The introduction for the whole thesis structure for each chapter is demonstrated in Chapter 1. And then, the design ideas and simulations on each component and assembly results are discussed chapter by chapter. Hopefully, the simulation design can provide an essential theoretical basis and reference for the first high-resolution interaction-free measurement experiment in the EM system in future.