In-situ Observations of Restructuring Carbon Nanotubes via Low-voltage Aberration-corrected Transmission Electron Micros
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In-situ Observations of Restructuring Carbon Nanotubes via Low-voltage Aberration-corrected Transmission Electron Microscopy Felix Börrnert1, Alicja Bachmatiuk1, Sandeep Gorantla1, Jamie H. Warner2, Bernd Büchner1, and Mark H. Rümmeli1,3 1 Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., PF 270116, 01171 Dresden, Germany 2 University of Oxford, Parks Road, Oxford OX13PH, United Kingdom 3 Technische Universität Dresden, 01062 Dresden, Germany ABSTRACT The molecular structure and dynamics of carbon nanostructures is much discussed throughout the literature, mostly from the theoretical side because of a lack of suitable experimental techniques to adequately engage the problem. A technique that has recently become available is low-voltage aberration-corrected transmission electron microscopy. It is a valuable tool with which to directly observe the atomic structure and dynamics of the specimen in situ. Time series aberration-corrected low-voltage transmission electron microscopy is used to study the dynamics of single-wall carbon nanotubes in situ. We confirm experimentally previous theoretical predictions for the agglomeration of adatoms forming protrusions and subsequent removal. A model is proposed how lattice reconstruction sites spread. In addition, the complete healing of a multi-vacancy consisting of ca. 20 missing atoms in a nanotube wall is followed. INTRODUCTION Single-walled carbon nanotubes (SWNTs) are promising for application in future electronic devices [1]. Defects in the nanotubes can alter their electronic properties and are therefore studied intensely [2]. The behavior of defects in SWNTs is much discussed, but in most of the cases theoretically because of the special difficulty in handling nano-sized structures experimentally [3]. The behavior of sp2 carbon under electron irradiation is of particular interest because of the possibilities that electron microscopes offer in the characterization and manipulation of this material. Smith and Luzzi calculate the carbon sp2 lattice to be stable against knock-on damage under electron irradiation up to electron energies of 86 keV [4]. The lattice is most susceptible to the electron beam when the incident beam is normal to the lattice plane. Graphene is a perfect system to test this. Meyer and coworkers found that a clean graphene lattice is not affected by high-dose 80 keV electron irradiation but is damaged by lower-dose 100 keV electrons [5]. SWNTs as rolled-up graphene show a diameter dependent stability. Warner et al. demonstrated that small diameter nanotubes are destroyed more quickly than larger ones [6]. Also, they show contamination on the lattice leads to rapid destruction in the electron beam. In electronic devices hetero-junctions are most desired. Molecular junctions consisting of nanotubes and organic molecules or even single carbon chains have been proposed [7,8]. A convenient way to produce junctions is to have SWNTs with different chirality connected. These could be produced by locally induced material loss and subsequen
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