Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Twisted X-rays: incoming waveforms yielding discrete diffraction
  patterns for helical structures   Conventional X-ray methods use incoming plane waves and result in discrete
diffraction patterns when scattered at crystals. Here we find, by a systematic
method, incoming waveforms which exhibit discrete diffraction patterns when
scattered at helical structures. As examples we present simulated diffraction
patterns of carbon nanotubes and tobacco mosaic virus.
  The new incoming waveforms, which we call twisted waves due to their
geometric shape, are found theoretically as closed-form solutions to Maxwell's
equations. The theory of the ensuing diffraction patterns is developed in
detail. A twisted analogue of the Von Laue condition is seen to hold, with the
peak locations encoding the symmetry and the helix parameters, and the peak
intensities indicating the electronic structure in the unit cell.
  If suitable twisted X-ray sources can in the future be realized
experimentally, it appears from our mathematical results that they will provide
a powerful tool for directly determining the detailed atomic structure of
numerous biomolecules and nanostructures with helical symmetries. This would
eliminate the need to crystallize those structures or their subunits.

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The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
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The categories of this paper are: eess
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn