Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic spectroscopy of medium-sized polycyclic aromatic
  hydrocarbons: Implications for the carriers of the 2175 {\AA} UV bump   Mixtures of polycylic aromatic hydrocarbons (PAHs) have been produced by
means of laser pyrolysis. The main fraction of the extracted PAHs were
primarily medium-sized, up to a maximum size of 38 carbon atoms per molecule.
The use of different extraction solvents and subsequent chromatographic
fractionation provided mixtures of different size distributions. UV-VIS
absorption spectra have been measured at low temperature by matrix isolation
spectroscopy and at room temperature with PAHs as film-like deposits on
transparent substrates. In accordance with semi-empirical calculations, our
findings suggest that large PAHs with sizes around 50 to 60 carbon atoms per
molecule could be responsible for the interstellar UV bump at 217.5 nm.

15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs