Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: InSe as a case between 3D and 2D layered crystals for excitons   We demonstrate the successive appearance of the exciton, biexciton, and P
band of the exciton-exciton scattering with increasing excitation power in the
photoluminescence of indium selenide layered crystals. The strict energy and
momentum conservation rules of the P band are used to reexamine the exciton
binding energy. The new value $\geq 20$ meV is markedly higher than the
currently accepted 14 meV, being however well consistent with the robustness of
excitons up to room temperature. A peak controlled by the Sommerfeld factor is
found near the bandgap ($\sim 1.36$ eV), which puts the question on the pure
three-dimensional character of the exciton in InSe, which has been assumed up
to now. Our findings are of paramount importance for the successful application
of InSe in nanophotonics.

24
The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex