Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Si Substitution in Nanotubes and Graphene via Intermittent Vacancies   The properties of single-walled carbon nanotubes (SWCNTs) and graphene can be
modified by the presence of covalently bound impurities. Although this can be
achieved by introducing chemical additives during synthesis, that often hinders
growth and leads to limited crystallite size and quality. Here, through the
simultaneous formation of vacancies with low-energy argon plasma and the
thermal activation of adatom diffusion by laser irradiation, silicon impurities
are incorporated into the lattice of both materials. After an exposure of
$\sim$1 ion/nm$^{2}$, we find Si substitution densities of 0.15 nm$^{-2}$ in
graphene and 0.05 nm$^{-2}$ in nanotubes, as revealed by atomically resolved
scanning transmission electron microscopy. In good agreement with predictions
of Ar irradiation effects in SWCNTs, we find Si incorporated in both mono- and
divacancies, with $\sim$2/3 being of the first type. Controlled inclusion of
impurities in the quasi-1D and 2D carbon lattices may prove useful for
applications such as gas sensing, and a similar approach might also be used to
substitute other elements with migration barriers lower than that of carbon.

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The categories of this paper are: math-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
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The categories of this paper are: eess
0
The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: plasm-ph