title: Atomistic description of electron beam damage in nitrogen-doped graphene and single-walled carbon nanotubes.
abstract: By combining ab initio simulations with state-of-the-art electron microscopy and electron energy loss spectroscopy, we study the mechanism of electron beam damage in nitrogen-doped graphene and carbon nanotubes. Our results show that the incorporation of nitrogen atoms results in noticeable knock-on damage in these structures already at an acceleration voltage of 80 kV, at which essentially no damage is created in pristine structures at corresponding doses. Contrary to an early estimate predicting rapid destruction via sputtering of the nitrogen atoms, in the case of substitutional doping, damage is initiated by displacement of carbon atoms neighboring the nitrogen dopant, leading to the conversion of substitutional dopant sites into pyridinic ones. Although such events are relatively rare at 80 kV, they become significant at higher voltages typically used in electron energy loss spectroscopy studies. Correspondingly, we measured an energy loss spectrum time series at 100 kV that provides direct evidence for such conversions in nitrogen-doped single-walled carbon nanotubes, in excellent agreement with our theoretical prediction. Besides providing an improved understanding of the irradiation stability of these structures, we show that structural changes cannot be neglected in their characterization employing high-energy electrons.
authors.affiliation: Nanomaterials Group, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, 00076 Aalto, Finland. toma.susi@aalto.fi
authors.forename: Toma
authors.initials: T
authors.lastname: Susi
authors.forename: Jani
authors.initials: J
authors.lastname: Kotakoski
authors.forename: Raul
authors.initials: R
authors.lastname: Arenal
authors.forename: Simon
authors.initials: S
authors.lastname: Kurasch
authors.forename: Hua
authors.initials: H
authors.lastname: Jiang
authors.forename: Viera
authors.initials: V
authors.lastname: Skakalova
authors.forename: Odile
authors.initials: O
authors.lastname: Stephan
authors.forename: Arkady V
authors.initials: AV
authors.lastname: Krasheninnikov
authors.forename: Esko I
authors.initials: EI
authors.lastname: Kauppinen
authors.forename: Ute
authors.initials: U
authors.lastname: Kaiser
authors.forename: Jannik C
authors.initials: JC
authors.lastname: Meyer
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D006108:Graphite / Q000737:chemistry* / Q000528:radiation effects*; D008956:Models, Chemical; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000528:radiation effects*; D009584:Nitrogen / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D037742:Nanotubes, Carbon; D006108:Graphite; D009584:Nitrogen