ExoMol molecular line lists XXXVI: \(X\ {}^2\Pi - X\ {}^2\Pi\) and \(A\ {}^2\Sigma^+ - X\ {}^2\Pi\) transitions of SH

Abstract

The GYT line list covering rotational, rovibrational and rovibronic transitions of the mercapto radical SH is presented. This work extends and replaces the SNaSH line list [Yurchenko et al., 2018, MNRAS, 478, 270] which covers the ground (electronic) \(X\) \(^{2}\Pi\) state only. This extension is prompted by the tentative identification of the ultra-violet features of SH as being of importance in the transmission spectrum of the ultra-hot Jupiter exoplanet WASP-121b [Evans et al., 2018, AJ., 156, 283]. This GYT line list model is generated by fitting empirical potential energy, spin-orbit and electronic angular momenta functions to experimentally measured wavelengths within the \(X\) \(^{2}\Pi\) and \(A\) \(^{2}\Sigma^{+}\) states and to the \(A\) \(^{2}\Sigma^{+}\) - \(X\) \(^{2}\Pi\) band system using ab initio curves as a starting reference point. The fits are compatible with the quoted uncertainty of the experimental data used of \(\sim\) 0.03 - 0.3 cm\(^{-1}\). The GYT line list covers wavelengths longer than 0.256 \(\mu\)m and includes 7686 rovibronic states and 572 145 transitions for \(^{32}\)SH. Line lists for the \(^{33}\)SH, \(^{34}\)SH, \(^{36}\)SH and \(^{32}\)SD isotopologues are generated including a consideration of non-Born-Oppenheimer effects for SD. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases.