Three-dimensional Atomic Dynamics of Peapods (C60/SWCNT) under Irradiation of Pulsed Electron

Abstract

In recent years, advancements of aberration-corrected transmission electron microscopy and data acquisition schemes such as electron tomography and holography have enabled online observation of electron-beam-induced chemical reactions at the atomic-scale, which is crucial for explaining bonding mechanisms, tracking atomic displacements and investigating 3D atomic dynamics. Here, we constructed an atomic-scale reaction system by encapsulating fullerenes inside single wall carbon nanotubes (SWCNTs), where the SWCNTs serve as the atomic-scale reaction vessel and fullerenes as the reactants. And we used more softer pulsed electron to control a low electron dose imaging mode to minimize irradiation damage and reduce the reaction rates of fullerenes and SWCNTs, where the length of beam pulse and electron does were 190 ns and 217 e-Å^-2 respectively. What’s more, we reconstructed the exit wave function from focal-series images and factorized the electron beam dose into each focal plane to further minimize irradiation damage; we also changed the number of focal-series images and got the exit waves with time resolution to further analyze 3D atomic resolution dynamics of peapod(C60/SWCNT) supramolecular assembly. In this work, we recorded that reversible dimerization reactions of fullerenes are accompanied by the breaking and formation of chemical bonds. Moreover, we analyzed the formation and transformation of SWCNT defects and vacancies in more detail, and even captured a 10-membered carbon ring prior to the formation of the 5-7 defect, which suggests the formation of the 5-7 defect is accomplished in a stepwise manner. In addition, we confirmed that the electron-induced atom is transferred along the axial direction of SWCNT by observing the transformation of vacancies.

Date of Award	2 Aug 2024
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Fu-Rong CHEN (Supervisor) & Xiaoyan ZHONG (Co-supervisor)