Interest include: chemistry of the troposphere in general; method development and deployment for the measurements of important atmospheric species; kinetic, mechanistic and thermodynamic study of atmospheric processes in the laboratory. The current research programs in my group are focused on the tropospheric chemistry of reactive nitrogen species and photochemistry of sea-salt aerosols. Specific ongoing research activities include: method development for the measurements of nitrous, nitric acids, and ammonia in the atmosphere; field measurements of these important species to establish their distributions and variations in the troposphere, and to elucidate the formation/transformation mechanisms of nitrogen species and photooxidants in the troposphere in both urban and rural environments; laboratory study to provide kinetic and mechanistic insights into HONO formation and reactive nitrogen cycling in the troposphere; measurements of photochemical productions of OH radical and other oxidants in sea-salt aerosols.