Neutral and Ion Photochemistry in Planetary Atmospheres

Understanding the chemical inventory of a planetary atmosphere is one of the outstanding interdisciplinary challenges in science.

One key process governing a planet’s composition, the detection of potential biosignatures, and the formation of life’s building blocks, is photochemistry. It is the dominant factor that shapes the neutral and ionized upper atmospheres of planets inside and outside the Solar System. Additionally, chemical interactions with radiation lie at the basis of several prominent and observable atmospheric phenomena, such as the formation of an ozone layer, airglow, hydrocarbon haze formation, and atmospheric escape. The recent serendipitous discovery of photochemically produced SO₂ in a hot exoplanet is a poignant illustration of the importance – but also our limited understanding – of photochemistry.

Through this Lorentz Center workshop we bring together experts in chemical kinetic modelling, laboratory chemistry, and radiation physics in order to tackle current challenges involving planetary upper atmospheres. This way, we aim to identify the important questions that need to be addressed in planetary photochemistry and construct a roadmap for the future. This workshop will encourage knowledge transfer between the chemistry, astronomy, and planetary science communities, and steer toward the development of new chemical data and novel neutral-ion chemical schemes that help understand Solar System and exoplanet upper atmospheres.