Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rotational spectra of N$_2^+$: An advanced undergraduate laboratory in
  atomic and molecular spectroscopy   We describe an inexpensive instructional experiment that demonstrates the
rotational energy levels of diatomic nitrogen, using the emission band spectrum
of molecular nitrogen ionized by various processes in a commercial AC capillary
discharge tube. The simple setup and analytical procedure is introduced as part
of a sequence of educational experiments employed by a course of advanced
atomic and molecular spectroscopy, where the study of rotational spectra is
combined with the analysis of vibrational characteristics for a multifaceted
picture of the quantum states of diatomic molecules.

24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat