Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bi-Arrhenius diffusion and surface trapping of $^{8}$Li$^{+}$ in rutile
  TiO$_2$   We report measurements of the diffusion rate of isolated ion-implanted
$^{8}$Li$^{+}$ within $\sim$120 nm of the surface of oriented single-crystal
rutile TiO$_2$ using a radiotracer technique. The $\alpha$-particles from the
$^{8}$Li decay provide a sensitive monitor of the distance from the surface and
how the depth profile of $^{8}$Li evolves with time. The main findings are that
the implanted Li$^{+}$ diffuses and traps at the (001) surface. The
T-dependence of the diffusivity is described by a bi-Arrhenius expression with
activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures
it has a much smaller barrier of 0.0313(15) eV. We consider possible origins
for the surface trapping, as well the nature of the low-T barrier.

29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
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The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math