Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Size effect in the ionization energy of PAH clusters   We report the first experimental measurement of the near-threshold
photo-ionization spectra of polycyclic aromatic hydrocarbon clusters made of
pyrene C16H10 and coronene C24H12, obtained using imaging photoelectron
photoion coincidence spectrometry with a VUV synchrotron beamline. The
experimental results of the ionization energy are confronted to calculated ones
obtained from simulations using dedicated electronic structure treatment for
large ionized molecular clusters. Experiment and theory consistently find a
decrease of the ionization energy with cluster size. The inclusion of
temperature effects in the simulations leads to a lowering of this energy and
to a quantitative agreement with the experiment. In the case of pyrene, both
theory and experiment show a discontinuity in the IE trend for the hexamer.

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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nlin
2
The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin