Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Imaging the potential distribution of individual charged impurities on
  graphene by low-energy electron holography   While imaging individual atoms can routinely be achieved in high resolution
transmission electron microscopy, visualizing the potential distribution of
individually charged adsorbates leading to a phase shift of the probing
electron wave is still a challenging task. Low-energy electrons (30 - 250 eV)
are sensitive to localized potential gradients. We employed low-energy electron
holography to acquire in-line holograms of individual charged impurities on
free-standing graphene. By applying an iterative phase retrieval reconstruction
routine we recover the potential distribution of the localized charged
impurities present on free-standing graphene.

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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
16
The categories of this paper are: stat
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The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
8
The categories of this paper are: hep-ex