Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Paramagnetic centers in graphene nanoribbons prepared from longitudinal
  unzipping of carbon nanotubes   Electron spin resonance (ESR) investigation of graphene nanoribbons (GNRs)
prepared through longitudinal unzipping of multiwalled carbon nanotubes
(MWCNTs) indicates the presence of C-related dangling bond centers, exhibiting
paramagnetic features. ESR signal broadening from pristine or oxidized graphene
nanoribbons (OGNRs) is explained in terms of unresolved hyperfine structure,
and in the case of reduced GNRs (RGNRs), the broadening of ESR signal can be
due to enhancement in conductivity upon reduction. The spin dynamics observed
from ESR linewidth-temperature data reflect a variable range hopping (VRH)
mechanism through localized states, consistent with resistance-temperature
data.

32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat