Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: N-nH complexes in GaAs studied at the atomic scale by cross-sectional
  scanning tunneling microscopy
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an