Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bright, Coherent, Ultrafast Soft X-Ray Harmonics Spanning the Water
  Window from a Tabletop Light Source   We demonstrate fully phase matched high-order harmonic generation with
emission spanning the water window spectral region important for bio- and
nano-imaging and a breadth of materials and molecular dynamics studies. We also
generate the broadest bright coherent bandwidth (~300eV) to date obtained from
any light source, small or large. The harmonic photon flux at 0.5 keV is 10^3
higher than demonstrated previously, making it possible for the first time to
demonstrate spatial coherence in the water window. The continuum emission is
consistent with a single attosecond burst, that extends bright attosecond
pulses into the soft x-ray region.

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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: cond-mat