Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Can the electronic energy spectra of bulk excitonic states be traced to
  parent molecular states in fluorene and its hetero-analogues? It depends on
  the mutual orientation of the respective transition dipoles in the crystal   The effect of intermolecular interactions on intensity redistribution between
individual electronic transitions in different polymorphs of fluorene and
dibenzofuran was studied by transmittance electronic spectroscopy in the energy
range from onset of absorption to the ionization energy (from ~4.0 eV to ~9.0
eV - Electronic transitions with transition dipoles at oblique angles to the
crystallographic axes (A1 symmetry) in these crystals resemble molecular
spectra. Transitions of B2 symmetry, which in these crystals have parallel
transition dipoles, resemble molecular spectra for surface (substrate
influenced) states. For bulk excitonic states the spectra of these transitions
have a continuous, uniform intensity distribution in the whole energy range
investigated, except for the case when the B2 transition is the onset of
absorption.

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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph