Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast x-ray-induced nuclear dynamics in diatomic molecules using
  femtosecond x-ray/x-ray pump-probe spectroscopy   The capability of generating two intense, femtosecond x-ray pulses with
controlled time delay opens the possibility of performing time-resolved
experiments for x-ray induced phenomena. We have applied this capability to
study the photoinduced dynamics in diatomic molecules. In molecules composed of
low-Z elements, \textit{K}-shell ionization creates a core-hole state in which
the main decay mode is an Auger process involving two electrons in the valence
shell. After Auger decay, the nuclear wavepackets of the transient
two-valence-hole states continue evolving on the femtosecond timescale, leading
either to separated atomic ions or long-lived quasi-bound states. By using an
x-ray pump and an x-ray probe pulse tuned above the \textit{K}-shell ionization
threshold of the nitrogen molecule, we are able to observe ion dissociation in
progress by measuring the time-dependent kinetic energy releases of different
breakup channels. We simulated the measurements on N$_2$ with a molecular
dynamics model that accounts for \textit{K}-shell ionization, Auger decay, and
the time evolution of the nuclear wavepackets. In addition to explaining the
time-dependent feature in the measured kinetic energy release distributions
from the dissociative states, the simulation also reveals the contributions of
quasi-bound states.

7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph