Organic Component Vapor Pressures and Hygroscopicities of Aqueous Aerosol Measured by Optical Tweezers
Organic Component Vapor Pressures and Hygroscopicities of Aqueous Aerosol Measured by Optical Tweezers
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DOI：
10.1021/jp510525r
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发表时间：
2015-01-29
影响因子：
2.9
通讯作者：
Clegg, Simon L.
中科院分区：
文献类型：
--
作者：
Cai, Chen;Stewart, David J.;Clegg, Simon L.
测量气溶胶的吸湿响应和半挥发性有机化合物的颗粒到气体的分配对于更准确地描述大气气溶胶的组成和尺寸分布是至关重要的。同时测量颗粒大小和组成(根据折射率推断)的报告在这里使用光学镊子在延长的时间范围内分离和探测单个气溶胶液滴。这些测量表明，通过检查含有水和单一有机成分的二元液滴的尺寸和组成的相关变化，可以准确地提取组分的蒸汽压和吸湿响应。报道了一系列二元酸、顺丁烯二酸、柠檬酸、甘油或1，2，6-己三醇的测量结果。当只测量颗粒尺寸时，对这种测量中的固有不确定度进行了评估，以确认这种相关方法的价值。我们还表明，摩尔折射率的方法提供了对溶液折射率组成依赖关系的准确表征。在这种方法中，纯液体溶质的密度是最大的不确定度，必须已知或从不饱和测量中推断出来，误差为
Measurements of the hygroscopic response of aerosol and the particle-to-gas partitioning of semivolatile organic compounds are crucial for providing more accurate descriptions of the compositional and size distributions of atmospheric aerosol. Concurrent measurements of particle size and composition (inferred from refractive index) are reported here using optical tweezers to isolate and probe individual aerosol droplets over extended timeframes. The measurements are shown to allow accurate retrievals of component vapor pressures and hygroscopic response through examining correlated variations in size and composition for binary droplets containing water and a single organic component. Measurements are reported for a homologous series of dicarboxylic acids, maleic acid, citric acid, glycerol, or 1,2,6-hexanetriol. An assessment of the inherent uncertainties in such measurements when measuring only particle size is provided to confirm the value of such a correlational approach. We also show that the method of molar refraction provides an accurate characterization of the compositional dependence of the refractive index of the solutions. In this method, the density of the pure liquid solute is the largest uncertainty and must be either known or inferred from subsaturated measurements with an error of