Extending ExoMol into the ultraviolet: Sulphur containing molecules

When a sulphur-containing molecule in an exoplanet’s atmosphere absorbs ultraviolet light, it can break apart at a rate that depends strongly on the molecule’s temperature—a detail current models largely ignore. The ExoMol database already provides the molecular data astronomers use to identify chemicals in exoplanet atmospheres, brown dwarfs, and cool stars. But it covers only visible and infrared light. Ultraviolet radiation drives key chemical reactions—especially photodissociation—that shape an atmosphere’s composition. Without temperature-dependent UV data, models of hot Jupiter or super-Earth atmospheres remain incomplete. This project will calculate how UV light affects water and sulphur-containing molecules (H₂S, SO₂, HS, SO, S₂) at different temperatures, starting from first-principles quantum chemistry and adjusting the results against known low-temperature cross sections. If successful, the work will add a new UV layer to the ExoMol database, freely available online. Astronomers will be able to model atmospheric chemistry more accurately, improving interpretations of exoplanet spectra from telescopes like JWST and Ariel. This is fundamental science—it will not change daily life directly—but it builds the kind of molecular knowledge that, in the past, has underpinned everything from climate modelling to industrial gas sensing.