ExoMol molecular line lists XXXVI: X 2Π – X 2Π and A 2Σ+ – X 2Π transitions of SH

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, which covers the ground (electronic) X 2Π state only. This extension is prompted by the tentative identification of the ultraviolet features of SH as being of importance in the transmission spectrum of the ultrahot Jupiter exoplanet WASP-121b. 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 2Π and A 2Σ+ states and to the A 2Σ+–X 2Π 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 ∼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 32SH. Line lists for the 33SH, 34SH, 36SH, and 32SD 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.