ExoMol line lists XXVIII: The rovibronic spectrum of AlH

TL;DR

This paper presents a comprehensive new line list for aluminum hydride (AlH), covering two electronic states and multiple isotopologues, useful for astrophysical and laboratory spectroscopy at high temperatures.

Contribution

It introduces a new, empirically fitted rovibronic line list for AlH, including potential energy curves, transition data, and lifetimes for three isotopologues, expanding available spectral data.

Findings

Line list covers $X$--$X$ and $A$--$X$ systems.

Includes partition functions and lifetimes for three isotopologues.

Data is publicly available in electronic databases.

Abstract

A new line list for AlH is produced. The WYLLoT line list spans two electronic states $X\,{}^1\Sigma^+$ and $A\,{}^1\Pi$. A diabatic model is used to model the shallow potential energy curve of the $A\,{}^1\Pi$ state, which has a strong pre-dissociative character with only two bound vibrational states. Both potential energy curves are empirical and were obtained by fitting to experimentally derived energies of the $X\,{}^1\Sigma^+$ and $A\,{}^1\Pi$ electronic states using the diatomic nuclear motion codes Level and Duo. High temperature line lists plus partition functions and lifetimes for three isotopologues $^{27}$AlH, $^{27}$AlD and $^{26}$AlH were generated using ab initio dipole moments. The line lists cover both the $X$--$X$ and $A$--$X$ systems and are made available in electronic form at the CDS and ExoMol databases.