Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Near-infrared photoluminescence from molecular crystals containing
  tellurium   We report the observation of near-infrared photoluminescence from
Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 molecular crystals containing Te42+ polycations.
The experimental and theoretical results clearly revealed that Te42+ polycation
is one smart near-infrared emitter with characteristic emission peaks at 1252
and 1258 nm for Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 crystals, respectively, resulting
from the intrinsic electronic transitions of Te42+. Furthermore, it was also
found that the emissions strongly depend on the excitation wavelengths for both
Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 samples, most possibly owing to the co-existence
of other Te-related optically active centers. This research not only enriches
the species of luminescent charged p-block element polyhedra and deepens the
understanding of Te-related photophysical behaviors, but also may stimulate
efforts for designing novel material systems using such active centers. It is
also greatly expected that these sub-nanometer optically active species could
exist in other systems such as glasses, polymers, and bulk optical crystals,
and the stabilization of these centers in widely used hosts will pave the way
for their practical applications.

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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: eess