Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A spectroscopic study of the cycling transition 4s[3/2]_2-4p[5/2]_3 at
  811.8 nm in Ar-39: Hyperfine structure and isotope shift   Doppler-free saturated absorption spectroscopy is performed on an enriched
radioactive Ar-39 sample. The spectrum of the 3s^2 3p^5 4s [3/2]_2 - 3s^2 3p^5
4p [5/2]_3 cycling transition at 811.8 nm is recorded, and its isotope shift
between Ar-39 and Ar-40 is derived. The hyperfine coupling constants A and B
for both the 4s [3/2]_2 and 4p [5/2]_3 energy levels in Ar-39 are also
determined. The results partially disagree with a recently published
measurement of the same transition. Based on earlier measurements as well as
the current work, the isotope shift and hyperfine structure of the
corresponding transition in Ar-37 are also calculated. These spectroscopic data
are essential for the realization of laser trapping and cooling of Ar-37 and
Ar-39.

10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph