Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum-Size Effects in the Visible Photoluminescence of Colloidal ZnO
  Quantum Dots: A Theoretical Analysis   In this work we develop a simple theory for the green photoluminescence of
ZnO quantum dots (QDs) that allows us to understand and rationalize several
experimental findings on fundamental grounds. We calculate the spectrum of
light emitted in the radiative recombination of a conduction band electron with
a deeply trapped hole and find that the experimental behavior of this emission
band with particle size can be understood in terms of quantum size effects of
the electronic states and their overlap with the deep hole.We focus the
comparison of our results on detailed experiments performed for colloidal ZnO
nanoparticles in ethanol and find that the experimental evolution of the
luminescent signal with particle sizeat room temperature can be better
reproduced by assuming the deep hole to be localized at the surface of the
nanoparticles. However, the experimental behavior of the intensity and decay
time of the signal with temperature can be rationalized in terms of holes
predominantly trapped near the center of the nanoparticles at low temperatures
being transferred to surface defects at room temperature. Furthermore, the
calculated values of the radiative lifetimes are comparable to the experimental
values of the decay time of the visible emission signal.We also study the
visible emission band as a function of the number of electrons in the
conduction band of the nanoparticle, finding a pronounced dependence of the
radiative lifetime but a weak dependence of energetic position of the maximum
intensity.

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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin