Particles in the micron-size range are levitated in a quadrupole trap while being exposed to varying levels of atmospheric gases. The quadrupole trap permits the observation of particle mass changes resulting from interaction of a particle with components of its gaseous environment. Candidate systems for study will include sulfuric acid droplets interacting with ammonia, the absorption by sodium chloride solutions of sulfuric acid and nitric acid vapors with release of hydrogen chloride, the production of sulfuric or nitric acid by exposure of sodium chloride solutions to SO2, NO2, O3, or H2 O2, the production of ammonium sulfate in solution droplets exposed to SO2, O3 and NH3, the production of sulfuric acid in sodium chloride solution droplets doped with iron group ions and exposed to SO2 and O2, and the production of ammonium sulfate at the surface of manganese sulfate particles exposed to H2O, O2, SO2 and NH3. Individual particles suspended in the trap will be exposed to flowing N2 containing one or more of the reactant gases while changes in mass and particle size (by light scattering) will be monitored. Results will be presented as rates of net change.
