title: Assessing and ameliorating the influence of the electron beam on carbon nanotube oxidation in environmental transmission electron microscopy.
abstract: In this work, we examine how the imaging electron beam can induce damage in carbon nanotubes (CNTs) at varying oxygen gas pressures and electron dose rates using environmental transmission electron microscopy (ETEM). Our studies show that there is a threshold cumulative electron dose which brings about damage in CNTs in oxygen - through removal of their graphitic walls - which is dependent on O2pressure, with a 4-5 fold decrease in total electron dose per decade increase at a lower pressure range (10-6to 10-5mbar) and approximately 1.3 -fold decrease per decade increase at a higher pressure range (10-3to 100mbar). However, at a given pressure, damage in CNTs was found to occur even at the lowest dose rate utilized, suggesting the absence of a lower limit for the latter parameter. This study provides guidelines on the cumulative dose required to damage nanotubes in the 10-7mbar to 100mbar pressure regimes, and discusses the role of electron dose rate and total electron dose on beam-induced CNT degradation experiments.
authors.affiliation: Stanford Nano Shared Facilities, Stanford University, Stanford, CA 94305, USA. Electronic address: alkoh@stanford.edu.
authors.forename: Ai Leen
authors.initials: AL
authors.lastname: Koh
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Sinclair
mesh_terms: D004583:Electrons; D046529:Microscopy, Electron, Transmission / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction / Q000187:drug effects; D010316:Particle Size
chemical_list: D037742:Nanotubes, Carbon
keywords: Beam damage; Carbon nanotubes; Electron dose; Environmental transmission electron microsccopy; Oxidation