Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Core-level photoemission time delay in heteronuclear diatomic molecules
  at high energy via multiple scattering theory   We present analytical expressions of momentum-resolved core-level
photoemission time delay in a molecular frame of a heteronuclear diatomic
molecule upon photoionization by a linearly polarized soft x-rays attosecond
pulse. For this purpose, we start to derive a general expression of
photoemission time delay based on the first order time dependent perturbation
theory within the one electron and single channel model in the fixed-in-space
system (atoms, molecules and crystals) and apply it to the core-level
photoemission within the electric dipole approximation. By using multiple
scattering theory and applying series expansion, plane wave and muffin-tin
approximations, the core-level photoemission time delay $t$ is divided into
three components, $t_{\rm abs}$, $t_{\rm path}$ and $t_{\rm sc}$, which are
atomic photoemission time delay, delays caused by the propagation of
photoelectron among the surrounding atoms and the scattering of photoelectron
by them, respectively. We applied single scattering approximation to $t_{\rm
path}$ and obtained $t_{\rm path}^{(1)}(k,\theta)$ with polarization vector
parallel to the molecular axis for a heteronuclear diatomic molecule, where
$\theta$ is the angle of measured photoelectron from the molecular axis. $t$ is
approximated well with this simplified expression $t_{\rm
path}^{(1)}(k,\theta)$ in the high energy regime ($k\gtrsim 3.5\,\, {\rm
a.u.}^{-1}$), and the validity of this estimated result is confirmed by
comparing it with multiple scattering calculations for C 1$s$ core-level
photoemission time delay of CO molecules. $t_{\rm path}^{(1)}(k,\theta)$ shows
characteristic dependence on $\theta$, it becomes zero at $\theta=0$, exhibits
EXAFS type oscillation with $2kR$ at $\theta=\pi$, where $R$ is the bondlength,
and gives just the travelling time of photoelectron from the absorbing atom to
the neighbouring atom at $\theta=\pi/2$.

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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex