Studying Planetary Hazes Using Tools Developed for Smog Chemistry

Atmospheric organic hazes are common in many planetary bodies in our solar system and likely exoplanet atmospheres as well. In addition, geochemical data supports the existence of an organic haze in early Earth's atmosphere. Organic aerosol is also prevalent in the atmosphere of Earth today contributing to photochemical smog, visibility degradation, as well as changes in radiative balance and cloud formation. A variety of in situ and remote sensing tools have been developed to probe the chemical, physical, and optical properties of Earth's particulate matter to identify sources and impacts. In part motivated by the arrival of the Huygens Probe at Titan, research in the Tolbert group has adapted these Earth based tools to study organic hazes formed in the laboratory under reducing conditions to simulate planetary atmospheres. We have observed that photochemical excitation of methane in nitrogen at far UV wavelengths results in nitrogen incorporation into aerosol particles, as well as nitrogen containing gases and ions. Addition of trace gases including oxygen reduce the amount of haze formed, but results in more oxygen in the particles. Recent work including reduced sulfur gases dramatically enhances haze formation and causes sulfur incorporation into particles. A summary of this work will be presented and outlook for the future discussed.