Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Formation and annihilation of nanocavities during keV ion irradiation of
  Ge   Nanocavities in Ge(111) created by 5 keV Xe ion irradiation are characterized
by ex situ transmission electron microscopy and Rutherford backscattering
spectrometry. Nanocavities nucleate near the surface and then undergo thermal
migration. Nanocavities with average diameter of 10 nm and areal density of 5.1
x 10-3 nm-2 are observed at 773 K, while nanocavities with average diameter of
2.9 nm and areal density of 3.1 x 10-3 nm-2 are observed at 673 K. The
estimated Xe gas pressure inside the nanocavities is 0.035 GPa at 773 K, much
smaller than the estimated equilibrium pressure 0.38 GPa. This result suggests
that the nanocavities grow beyond equilibrium size at 773 K. The nanocavities
are annihilated at the surface to form surface pits by the interaction of
displacement cascades of keV Xe ions with the nanocavities. These pits are
characterized by in situ scanning tunneling microscopy. Pits are created on
Ge(111) and Ge(001) at temperatures ~ 523-578 K by keV Xe ions even when less
than a bilayer (monolayer) of surface material is removed.

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The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph