Sulfur gases substantially affect the photochemistry of planetary atmospheres in our Solar System, and are expected to be important components in exoplanet atmospheres. However, sulfur photochemistry in the context of exoplanets is poorly understood due to a lack of chemical kinetics information for sulfur species under relevant conditions. Here, we study the photochemical role of hydrogen sulfide (H₂S) in warm CO₂-rich exoplanet atmospheres (800 K) by carrying out laboratory simulations. We find that H₂S plays a prominent role in photochemistry, even when present in the atmosphere at relatively low concentrations (1.6%). It participates in both gas and solid phase chemistry, leading to the formation of other sulfur gas products (CH₃SH/SO, C₂H₄S/OCS, SO₂/S₂ and CS₂) and to an increase in solid haze particle production and compositional complexity. Our study shows that we may expect thicker haze with small particle sizes (20–140 nm) for warm CO₂-rich exoplanet atmospheres that possess H₂S.

硫气体会严重影响我们太阳系中行星大气的光化学，并且有望成为系外行星大气中的重要成分。但是，由于缺乏有关条件下硫物质的化学动力学信息，因此对系外行星环境中的硫光化学了解甚少。在这里，我们通过进行实验室模拟研究了硫化氢（H ₂ S）在富含CO _2的温暖系外行星大气（800 K）中的光化学作用。我们发现，即使在大气中以相对较低的浓度（1.6％）存在时，H ₂ S在光化学中也起着重要作用。它同时参与气相和固相化学反应，导致形成其他硫气产物（CH ₃SH / SO，C ₂ H ₄ S / OCS，SO ₂ / S ₂和CS ₂），并增加了固体雾度颗粒的产生和成分复杂性。我们的研究表明，对于拥有H ₂ S的温暖的富含CO _2的系外行星大气，我们可能期望雾度较小（20-140 nm）的情况下更厚。