Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Study of photoinduced valence dynamics in
  EuNi$_2$(Si$_{0.21}$Ge$_{0.79}$)$_2$ through time-resolved X-ray absorption
  spectroscopy   The photoinduced valence dynamics of EuNi$_2$(Si$_{0.21}$Ge$_{0.79}$)$_2$ are
investigated using time-resolved X-ray absorption spectroscopy for Eu
$M_5$-edge. Through the pump-probe technique with synchrotron X-ray and
Ti:sapphire laser pulse, a photoinduced valence transition is observed from
Eu$^{3+}$ to Eu$^{2+}$. Because the lifetime of a photoinduced state can be up
to 3 ns, a metastable state is considered to be realized. By comparing the
experimental results with the theoretical calculations, the photoinduced
valence transition between Eu 4$f$ and conduction electrons is quantitatively
evaluated.

33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg