The objective of this project is to perform cloud chamber studies of heterogeneous SO oxidation by combustion products. The proposed 2 experiments seek to provide answers to the following questions: (1) How do combustion conditions influence heterogeneous SO oxidation? (2) How 2 does the chemical modification of particle surfaces in the flame and postflame region influence their cloud nucleation properties? (3) How does phase change of water vapor influence SO oxidation at room and 2 subfreezing temperatures? These questions will be answered in a series of experiments with an experimental cloud chamber. The chamber is coupled to a combustor, which is a source of cloud nucleation particles and reactive particulate and gaseous species. The chamber can be operated in a wide temperature range and enables collection of cloud water interstitial and total (cloud + interstitial) aerosol for chemical analysis and real-time measurement of soot content and cloud and interstitial aerosol
