Optical Emissions from Photoexcitation of Atmospheric Radicals and Molecules in the Gas Phase and on Aerosol Surfaces

点击翻译按钮获取中文摘要

The project is devoted primarily to atmospheric aerosols. Laboratory experiments will probe the conditions under which aerosols of ammonium sulfate and ammonium bisulfate can be formed in the gas phase from ammonia, sulfur trioxide and water vapor. The aerosols will be produced by mixing the reacting gases in a flow tube. Particle-size distributions of the resulting aerosols will be deduced from measurements of ultraviolet light scattering. Experiments will assess the possibility of chemically identifying such aerosols by observing light emitted by them when they are exposed to laser beams of variable wavelength and intensity. Variations of these experiments will test possibilities of separately detecting chemical species adhering to the surfaces of the aerosol particles. Similar experiments will be conducted on the formation of ammonium nitrate aerosols from ammonia, water vapor, nitric acid and/or nitrogen dioxide. The experiments will be useful for better understanding of conditions under which these aerosols are formed in both the natural and the perturbed atmosphere. The feasibility of measuring the aerosols under field conditions will be explored. Experiments aimed at detecting chemical species adhering to the aerosol surfaces are designed to reveal any unsuspected surface- chemical properties of the aerosols, by virtue of which they might influence the chemistry of the gas phase.