Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The hyperfine structure in the rotational spectrum of CF+   Context. CF+ has recently been detected in the Horsehead and Orion Bar
photo-dissociation regions. The J=1-0 line in the Horsehead is double-peaked in
contrast to other millimeter lines. The origin of this double-peak profile may
be kinematic or spectroscopic. Aims. We investigate the effect of hyperfine
interactions due to the fluorine nucleus in CF+ on the rotational transitions.
Methods. We compute the fluorine spin rotation constant of CF+ using high-level
quantum chemical methods and determine the relative positions and intensities
of each hyperfine component. This information is used to fit the theoretical
hyperfine components to the observed CF+ line profiles, thereby employing the
hyperfine fitting method in GILDAS. Results. The fluorine spin rotation
constant of CF+ is 229.2 kHz. This way, the double-peaked CF+ line profiles are
well fitted by the hyperfine components predicted by the calculations. The
unusually large hyperfine splitting of the CF+ line therefore explains the
shape of the lines detected in the Horsehead nebula, without invoking intricate
kinematics in the UV-illuminated gas.

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The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph