Publication

Three-dimensional ab initio description of vibration-assisted electron knock-on displacements in graphene

Mukesh Kumar Tripathi
2022
Journal paper
Abstract

Transmission electron microscopy characterization may damage materials, but an electron beam can also induce interesting dynamics. Elastic knock-on is the main electron irradiation damage mechanism in metals including graphene, and although atomic vibrations influence its cross section, only the out-of-plane direction has been considered so far. Here, we present a full three-dimensional first-principles theory of knock-on displacements including the effect of temperature on vibrations to describe dynamics into arbitrary directions. We validate the model with previously precisely measured knock-on damage of pristine graphene, where we show that the isotropic out-of-plane approximation correctly describes the cross section. We then apply our methodology to reversible jumps of pyridinic nitrogen atoms, whose probability under irradiation is measured at 55 and 60 keV. Direct displacement requiring a high emission angle and an alternative pathway via intermittent N adatom creation and recombination are computationally explored but are unable to explain the observed rates, implying stronger inelastic effects at the defect than in pristine graphene.

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Related concepts (26)
Potential applications of graphene
Potential graphene applications include lightweight, thin, and flexible electric/photonics circuits, solar cells, and various medical, chemical and industrial processes enhanced or enabled by the use of new graphene materials. In 2008, graphene produced by exfoliation was one of the most expensive materials on Earth, with a sample the area of a cross section of a human hair costing more than 1,000asofApril2008(about1,000 as of April 2008 (about 100,000,000/cm2). Since then, exfoliation procedures have been scaled up, and now companies sell graphene in large quantities.
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