Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray imaging of chemically active valence electrons during a pericyclic
  reaction   Time-resolved imaging of chemically active valence electron densities is a
long sought goal, as these electrons dictate the course of chemical reactions.
However, x-ray scattering is always dominated by the core and inert valence
electrons, making time-resolved x-ray imaging of chemically active valence
electron densities extremely challenging. To image such electron densities, we
demonstrate an effective and robust method, which emphasizes the information
encoded in weakly scattered photons. The degenerate Cope rearrangement of
semibullvalene, a pericyclic reaction, is used as an example to visually
illustrate our approach. Our work also provides experimental access to the
long-standing problem of synchronous versus asynchronous bond formation and
breaking during pericyclic reactions.

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The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
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The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph