Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct observation of interatomic Coulombic decay and subsequent
  ion-atom scattering in helium nanodroplets   We report on the experimental observation of interatomic Coulombic decay
(ICD) in pure $^4$He nanoclusters of mean sizes between $N \approx$ 5000 and
30000 and the subsequent scattering of energetic He$^+$ fragments inside the
neutral cluster by using cold target recoil ion momentum spectroscopy. ICD is
induced in He clusters by using vacuum ultraviolet light of $h\nu =$ 67 eV from
the BESSY II synchrotron. The electronic decay creates two neighboring ions in
the cluster at a well-defined distance. The measured fragment energies and
angular correlations show that a main energy loss mechanism of these ions
inside the cluster is a single hard binary collision with one atom of the
cluster.

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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph