Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The FERRUM project: Experimental lifetimes and transition probabilities
  from highly excited even 4d levels in Fe ii   We report lifetime measurements of the 6 levels in the 3d6(5D)4d e6G term in
Fe ii at an energy of 10.4 eV, and f -values for 14 transitions from the
investigated levels. The lifetimes were measured using time-resolved
laser-induced fluorescence on ions in a laser-produced plasma. The high
excitation energy, and the fact that the levels have the same parity as the the
low-lying states directly populated in the plasma, necessitated the use of a
two-photon excitation scheme. The probability for this process is greatly
enhanced by the presence of the 3d6(5D)4p z6F levels at roughly half the energy
difference. The f -values are obtained by combining the experimental lifetimes
with branching fractions derived using relative intensities from a hollow
cathode discharge lamp recorded with a Fourier transform spectrometer. The data
is important for benchmarking atomic calculations of astrophysically important
quantities and useful for spectroscopy of hot stars.

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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: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: q-alg