There is increasing evidence that heterogeneous processes involving cloud droplets, ice particles, and aerosols play an important role in global tropspheric chemistry. As a contribution to unraveling the many complex phenomena involved, the PI proposes to undertake investigations of a wide range of reactions pertaining to the chemistry of nitrogen containing species of atmospheric importance. The details of the molecular processes will be investigated through three major activities. The first will involve contribution to unraveling the complex chemistry associated with oxides of nitrogen, nitric acid and nitrosyl sulfuric acid, and ammonia in the troposphere. The second phase of the work will encompass thermochemical measurements which will provide information on the energetics of the reactions, and particularly on the stability of complexes which are likely to be important in the condensation of nitrogen containing species and in their gas-to-particle conversion. The third area of study will comprise investigations of the structure, growth and nucleation of aqueous phase clusters and ice-like crystals. The overall aim of the work is to provide complementary data which will serve to elucidate a number of the physical and chemical phenomena at the molecular level, through an investigation of reactions which have been proposed to be of particular importance on the basis of modeling calculations, atmospheric measurements, and other laboratory studies. The approach is to study clusters of ever increasing degrees of hydration that serve to bridge the regime from the small cluster domain to the macroscopic particle state. Recent advances in out laboratory enable us to investigate transformations over this entire range of particle size.
