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

该项目主要致力于研究大气中的气溶胶。实验室实验将探索氨、三氧化硫和水蒸气在气相中形成硫酸铵和硫酸氢铵气溶胶的条件。气溶胶将通过在流动管中混合反应气体而产生。由此产生的气溶胶的粒径分布将从紫外光散射的测量中推断出来。实验将通过观察这些气溶胶暴露在不同波长和强度的激光束下所发出的光，来评估用化学方法识别这些气溶胶的可能性。这些实验的变化将测试单独检测附着在气溶胶颗粒表面的化学物质的可能性。将对氨、水蒸气、硝酸和/或二氧化氮形成硝酸铵气溶胶进行类似的实验。这些实验将有助于更好地了解这些气溶胶在自然和扰动大气中形成的条件。探讨在野外条件下测量气溶胶的可行性。旨在检测附着在气溶胶表面的化学物质的实验，旨在揭示气溶胶的任何未预料到的表面化学性质，因为它们可能影响气相的化学性质。

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.