Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Enhanced thermal stability and spin-lattice relaxation rate of N@C60
  inside carbon nanotubes   We studied the temperature stability of the endohedral fullerene molecule,
N@C60, inside single-wall carbon nanotubes using electron spin resonance
spectroscopy. We found that the nitrogen escapes at higher temperatures in the
encapsulated material as compared to its pristine, crystalline form. The
temperature dependent spin-lattice relaxation time, T_1, of the encapsulated
molecule is significantly shorter than that of the crystalline material, which
is explained by the interaction of the nitrogen spin with the conduction
electrons of the nanotubes.

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The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
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The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
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The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
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The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
3
The categories of this paper are: physics