单颗粒气溶胶液滴吸湿挥发特性研究  

Research on Hygroscopicity and Volatility of Single Aerosol Droplet

作　　者：仝玉恺 方藤 柳瑶瑶 赵东平 叶安培[1] TONG Yukai;FANG Teng;LIU Yaoyao;ZHAO Dongping;YE Anpei(Key Laboratory for the Physics and Chemistry of Nanodevices,Department of Electronics,School of Electronics Engineering and Computer Science,Peking University,Beijing 100871,China)

机构地区：[1]北京大学信息科学技术学院电子学系纳米器件物理与化学教育部重点实验室,北京100871

出　　处：《大气与环境光学学报》2020年第6期486-495,共10页Journal of Atmospheric and Environmental Optics

基　　金：国家重点研发计划,2017YFC0209504。

摘　　要：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。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 aerosol evolution process, analyzing evolution motivation and predicting evolution path. Thus accurate single particle measurement 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 the hygroscopic-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 resonance Raman signal of the single droplet particle and combining with the appropriate physical models, we accurately measured the particle size, refractive index, diffusion coefficient, volatile flux and other important physicochemical parameters of the sodium chloride, sucrose and citric acid in the hygroscopic-volatile process. Moreover, the effects of 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 for understanding the hygroscopic-volatilization process of actual atmospheric aerosol.

关 键 词：气溶胶液滴 吸湿性 挥发性 拉曼光镊 

分 类 号：O439[机械工程—光学工程] O648.18[理学—光学]