Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cross-polarized optical absorption of single-walled nanotubes probed by
  polarized photoluminescence excitation spectroscopy   Cross-polarized absorption peaks of isolated single-walled carbon nanotubes
were observed by a polarized photoluminescence excitation (PLE) spectroscopy.
Using a simple theory for PL anisotropy, the observed PLE spectra are
decomposed into 'pure' components of the photoexcitation for incident light
polarized parallel and perpendicular to the SWNT axis. For several (n, m)
SWNTs, distinct peaks corresponding to perpendicular excitation were observed.
The measured transition energies for perpendicular excitations were
blue-shifted compared to the qualitative values predicted within a
single-particle theory. The results indicate a smaller exciton binding energy
for perpendicular excitations than for parallel excitations.

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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th