Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unique photoluminescence response of MoS2 quantum dots over wide range
  of As (III) in aqueous media   Solvothermal synthesis of MoS2 based quantum dots (QDs) and the performance
evaluation of bare QDs for the detection of aqueous As (III) oxidative state at
room temperature and neutral pH over an extremely wide range (0.1 ppb to 1000
ppb) is reported here. Concentration-dependent photoluminescence (PL) of the
QDs was found to be enhanced up to 50 ppb and then suppressed till 1000 ppb,
showing two distinctive slopes for enhancement and suppression. Passivation of
trap states or defects of QDs may be the possible reason for enhancement, and
the formation of extremely small glassy As2S3 particles on the QD surface may
be the possible reason for suppression. The pattern of optical absorption of
QDs is featureless but shows an enhanced absorbance in the near UV range below
300 nm, which increases with As (III) concentration up to 50 ppb and then
decreases following the PL pattern. The MoS2 QDs were characterized by
transmission electron microscopy (TEM), Xray diffraction (XRD), UV-Vis, and PL
spectroscopy. The enhancement and suppression results can be fitted excellently
with the modified Stern-Volmer equation, and the detection of arsenic is
possible using these linear fit equations as calibration curves.

37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
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The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: stat
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat