# Rotational spectroscopy of AlO: Low N transitions of astronomical interest in the X^2 Sigma^+ state

## TL;DR

This paper revisits the rotational spectrum of AlO's ground state, providing detailed line predictions to assist astronomers in detecting and analyzing AlO in space, especially in low N transitions of astronomical interest.

## Contribution

It offers a comprehensive recalculation of AlO's rotational lines in the ground state, resolving discrepancies and aiding future astronomical observations.

## Key findings

- Identified discrepancies in gamma_D values between Fourier and microwave data.
- Provided a list of calculated rotational lines up to N' = 11 for v=0,1,2 levels.
- Facilitated future searches and analysis of AlO in astronomical sources.

## Abstract

The detection of rotational transitions of the AlO radical at millimeter wavelengths from an astronomical source has recently been reported. In view of this, rotational transitions in the ground X^2 Sigma^+ state of AlO have been reinvestigated. Comparisons between Fourier transform and microwave data indicate a discrepancy regarding the derived value of gamma_D in the v = 0 level of the ground state. This discrepancy is discussed in the light of comparisons between experimental data and synthesized rotational spectra in the v = 0, 1 and 2 levels of X^2 Sigma^+. A list of calculated rotational lines in v = 0, 1 and 2 of the ground state up to N' = 11 is presented which should aid astronomers in analysis and interpretation of observed AlO data and also facilitate future searches for this radical.