Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Saturated absorption spectroscopy of buffer-gas-cooled Barium
  monofluoride molecules   We report an experimental investigation on the Doppler-free saturated
absorption spectroscopy of buffer-gas-cooled Barium monofluoride (BaF)
molecules in a 4~K cryogenic cell. The obtained spectra with a resolution of
19~MHz, much smaller than previously observed in absorption spectroscopy,
clearly resolve the hyperfine transitions. Moreover, we use these
high-resolution spectra to fit the hyperfine splittings of excited $A(v=0)$
state and find the hyperfine splitting of the laser-cooling-relevant
$A^2\Pi_{1/2}(v=0, J=1/2, +)$ state is about 18 MHz, much higher than the
previous theoretically predicted value. This provides important missing
information for laser cooling of BaF molecules.

18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph