单颗粒气溶胶液滴吸湿挥发特性研究#br#

大气气溶胶粒子的热动力学过程主要源于多元物质的非理想混合, 其演化过程包括液-液相分离、吸湿-挥发、非平衡传质等。相关物理化学参数是理解气溶胶演化过程、分析演化动因、预测演化路径的基础, 而精确的单粒子测量是获取这些重要参数的关键。利用自主开发的气溶胶拉曼光镊系统, 实现了单颗粒气溶胶液滴无接触长时间捕获, 并通过改变气溶胶粒子所处环境的相对湿度, 模拟了实际大气中悬浮气溶胶液滴的吸湿-挥发热力学演化过程。通过测量单颗粒液滴粒子的腔共振拉曼光谱信号, 结合相应的物理模型精确测量了氯化钠、蔗糖和柠檬酸三种不同气溶胶液滴粒子在吸湿-挥发过程中的粒径、折射率、扩散系数、挥发通量等重要物化参数, 分析了有机/无机气溶胶液滴的吸湿-挥发特性对相对湿度变化的不同响应以及气溶胶液滴可能存在的玻璃态、胶态等相变行为, 为理解实际大气气溶胶吸湿-挥发过程提供了重要参考。

Research on Hygroscopicity and Volatility ofSingle Aerosol Droplet#br#

The thermodynamic process of atmospheric aerosol particles is mainly derived from the non-ideal mixing of multiple substances, which includes liquid-liquid phase separation, hygroscopic-volatilization, and nonequilibrium mass transfer. Relevant physical and chemical parameters are the basis for understanding aerosolevolution process, analyzing evolution motivation and predicting evolution path. Thus accurate single particlemeasurement is the key to obtain these important parameters. In this study, single aerosol droplet capture without contact for a long time is realized by using the self-developed aerosol Raman optical tweezers system, and thehygroscopic-volatilization thermodynamic evolution process of aerosol droplets in the actual atmosphere is simulated by changing the ambient relative humidity around aerosol particles. Through measuring the cavity resonanceRaman signal of the single droplet particle and combining with the appropriate physical models, we accuratelymeasured the particle size, refractive index, diffusion coefficient, volatile flux and other important physicochemicalparameters of the sodium chloride, sucrose and citric acid in the hygroscopic-volatile process. Moreover, the effectsof relative humidity on hygroscopic-volatilization process for organic and inorganic aerosols, as well as the possible phase transitions such as glassy and gel transition, are investigated, which provide an important reference forunderstanding the hygroscopic-volatilization process of actual atmospheric aerosol.