Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic structures of Zn$_{1-x}$Co$_x$O using photoemission and x-ray
  absorption spectroscopy   Electronic structures of Zn$_{1-x}$Co$_x$O have been investigated using
photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The
Co 3d states are found to lie near the top of the O $2p$ valence band, with a
peak around $\sim 3$ eV binding energy. The Co $2p$ XAS spectrum provides
evidence that the Co ions in Zn$_{1-x}$Co$_{x}$O are in the divalent Co$^{2+}$
($d^7$) states under the tetrahedral symmetry. Our finding indicates that the
properly substituted Co ions for Zn sites will not produce the diluted
ferromagnetic semiconductor property.

37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph