Electron irradiation-induced destruction of carbon nanotubes in electron microscopes

Mølhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Chris; Horsewell, A.; Bøggild, Peter

doi:10.1016/j.ultramic.2007.03.001

Cited by 66 publications

(52 citation statements)

References 15 publications

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“…(18a) and (18b), with increasing depth inside the material the contribution of surface losses to the DCS rapidly diminishes whereas that from bulk losses increases until, eventually, the total DCS approaches its asymptotic bulk limit described by Eq. (17). This is illustrated in Fig.…”

Section: B Near Surface Regionmentioning

confidence: 91%

“…(18a) and (18b) do not reduce to the asymptotic bulk expression, Eq. (17). Obviously, this deficiency is less of a problem for nanostructures.…”

Section: B Near Surface Regionmentioning

confidence: 99%

“…It is now clear that low-energy electron-beam irradiation in scanning electron microscopy (SEM) or electron beam lithography (EBL), can efficiently alter CNT properties as a result of local chemical reactions mediated by the presence of gas radicals. [13][14][15][16][17] Direct inelastic effects in CNTs have also been reported (see Ref. 18, and references therein) but the mechanism is still not clear [19][20][21] given that CNTs are either metallic or narrow-gap semiconductors with delocalized electronic excitations having relatively short relaxation times.…”

Section: Introductionmentioning

confidence: 99%

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Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

Kyriakou

Emfietzoglou

García-Molina

et al. 2011

Journal of Applied Physics

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The effect of bulk and surface excitations to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes (MWNTs) is studied using the dielectric formalism. Calculations are based on a semiempirical dielectric response function for MWCNTs determined by means of a many-pole plasmon model with parameters adjusted to available experimental spectroscopic data under theoretical sum-rule constrains. Finite-size effects are considered in the context of electron gas theory via a boundary correction term in the plasmon dispersion relations, thus, allowing a more realistic extrapolation of the electronic excitation spectrum over the whole energy-momentum plane. Energy-loss differential and total inelastic scattering cross sections as a function of electron energy and distance from the surface, valid over the energy range $50-30,000 eV, are calculated with the individual contribution of bulk and surface excitations separated and analyzed for the case of normally incident and escaping electrons. The sensitivity of the results to the various approximations for the spatial dispersion of the electronic excitations is quantified. Surface excitations are shown to have a strong influence upon the shape and intensity of the energy-loss differential cross section in the near surface region whereas the general notion of a spatially invariant inelastic mean free path inside the material is found to be of good approximation.

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Section: B Near Surface Regionmentioning

confidence: 91%

“…(18a) and (18b) do not reduce to the asymptotic bulk expression, Eq. (17). Obviously, this deficiency is less of a problem for nanostructures.…”

Section: B Near Surface Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

Kyriakou

Emfietzoglou

García-Molina

et al. 2011

Journal of Applied Physics

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“…During imaging, however, energetic electrons in the TEM can give rise to production of defects due to ballistic displacements of atoms from the sample and beam-stimulated chemical etching [19], as studies on h-BN membranes also indicate [15][16][17]20].…”

mentioning

confidence: 99%

Two-Dimensional Transition Metal Dichalcogenides under Electron Irradiation: Defect Production and Doping

et al. 2012

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Using first-principles atomistic simulations, we study the response of atomically-thin layers of transition metal dichalcogenides (TMDs) -a new class of two-dimensional inorganic materials with unique electronic properties -to electron irradiation. We calculate displacement threshold energies for atoms in 21 different compounds and estimate the corresponding electron energies required to produce defects. For a representative structure of MoS2, we carry out high-resolution transmission electron microscopy experiments and validate our theoretical predictions via observations of vacancy formation under exposure to a 80 keV electron beam. We further show that TMDs can be doped by filling the vacancies created by the electron beam with impurity atoms. Thereby, our results not only shed light on the radiation response of a system with reduced dimensionality, but also suggest new ways for engineering the electronic structure of TMDs. [6,7]. Recently, TMDs with a common structural formula MeX 2 , where Me stands for transition metals (Mo, W, Ti, etc.) and X for chalcogens (S, Se, Te), have received considerable attention. These 2D materials are expected to have electronic properties varying from metals to wide-gap semiconductors, similar to their bulk counterparts [8,9], and excellent mechanical characteristics [10]. The monolayer TMD materials have already shown a good potential in nanoelectronic [3,11,12] and photonic [4,13,14] applications.Characterization of the h-BN [15-17] and TMD [5,6,18] samples has extensively been carried out using high-resolution transmission electron microscopy (HR-TEM). During imaging, however, energetic electrons in the TEM can give rise to production of defects due to ballistic displacements of atoms from the sample and beam-stimulated chemical etching [19], as studies on h-BN membranes also indicate [15][16][17]20].Contrary to h-BN, very little is known about the effects of electron irradiation on TMDs. So far, atomic defects have been observed via HR-TEM in WS 2 nanoribbons encapsulated inside carbon nanotubes at electron acceleration voltage of 60 kV [21] as well as at the edges of MoS 2 clusters under 80 kV irradiation [22], while no significant damage or amorphization was reported for MoS 2 sheets at 200 kV [18] -a surprising result taking into account the relatively low atomic mass of the S atom. Clearly, precise microscopic knowledge of defect production in TMDs under electron irradiation is highly desirable for assessing the effects of the beam on the samples. This knowledge would allow designing experimental conditions required to minimize damage, as well as developing beam-mediated post-synthesis doping techniques. Moreover, information on the displacement thresholds is important in the context of fundamental aspects of the interaction of beams of energetic particles with solids, as the reduced dimensionality may give rise to an irradiation response different from that in the bulk counterpart of the 2D material [23].Here, by employing first-principles simulations, we study the ...

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“…Although the use of low operating voltage is usually effective for observing materials composed of light elements, e.g., below 100 keV for carbon materials such as nanotubes [10][11] and graphene [12], this method may be unsuitable for observing light metal hydrides due to the excessively low threshold energy of displacement for hydrogen (and lithium), as well as the excessive energy transfer from incident electrons to hydrogen (and lithium) nuclei. In this study, the effects of constituting element and incident-electron energy on the irradiation damage to lithium, sodium, and magnesium hydrides (LiH, NaH, and MgH2) in the TEM were theoretically and experimentally investigated.…”

mentioning

confidence: 99%

Interaction of electrons with light metal hydrides in the transmission electron microscope

et al. 2014

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Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium, and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in-situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage. signals resulting from these phenomena allow for powerful microscopy and spectrometry applications in the TEM, e.g., imaging, diffraction, energy dispersive X-ray spectroscopy (EDS), and electron energy-loss spectrometry (EELS). However, these advantages are associated with detrimental beam damage, which limits the application of the TEM in materials that are sensitive to high-energy electron radiation.Unfortunately, most advanced hydrogen storage materials consisting of light elements are partially subject to this limitation. To achieve a high hydrogen capacity [1][2], the majority of currently studied hydrogen storage materials are composed of compounds and complexes containing light elements [3] such as lithium, sodium, and magnesium. These materials are

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Electron irradiation-induced destruction of carbon nanotubes in electron microscopes

Cited by 66 publications

References 15 publications

Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

Two-Dimensional Transition Metal Dichalcogenides under Electron Irradiation: Defect Production and Doping

Interaction of electrons with light metal hydrides in the transmission electron microscope

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