气溶胶双微粒的俘获、悬浮、碰并动态过程原位光谱观测

项目名称： 气溶胶双微粒的俘获、悬浮、碰并动态过程原位光谱观测

项目编号： No.21473009

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 张韫宏

作者单位： 北京理工大学

项目金额： 90万元

中文摘要： 气溶胶的基本物理化学过程，除了与气相物种进行交换、反应以外，还有一个重要的历程就是气溶胶颗粒之间的碰并过程，包括气溶胶颗粒之间的接触、融合、包覆、扩散、反应、触发相变等细节，这些细节是决定气溶胶尺寸、化学组成、相变、化学反应的关键因素，由于缺乏有效实验手段和观测方法，成为气溶胶领域的薄弱环节。本项目建立可以同时捕获、悬浮、控制两个气溶胶颗粒的光镊技术，开展气溶胶微粒碰并动态过程的原位光谱观测，其优势在于：（1）两个微粒的化学组成可控，（2）液滴的浓度、尺寸可以由灵敏的腔增强拉曼光谱进行时间分辨原位测量，（3）碰并过程可以实现操控，（4）碰并后的复合液滴的动态过程可以原位拉曼检测。本项目针对颗粒物碰并过程涉及的科学问题，建立双光镊技术，实现两个气溶胶微粒的捕获、悬浮、碰并动态过程的原位光谱观测，对液/液、液/固、固/固气溶胶微粒间碰并动态过程进行详细研究，从而揭示气溶胶由外混到内混的机制。

中文关键词： 拉曼光谱学；光镊；气溶胶；碰并

英文摘要： Coagulation between aerosol particles is a key process for PM2.5 beside the reaction between the particles and pollution gas. Such coagulation process incldes contacting, amalgamation, overlay, diffusion, reaction and phase transition between two particles, which determine the size, composition, phase state and reaction kinetics of aerosol. Understanding coagulation is limited because of a lack of effective experimental method. In this project, we try to set up double optical tweezers to trap two particles/droplets. Combined with in-situ Raman tecnnique spectroscopy, the detail coagulation process will be probed between two particles. The advantages of the double optical tweezers are taken of that (1) the composition of two particles can be confirmed,(2) the concentration, size of the droplets can be determined by the stimulation Raman spectra,(3) the coagulation can be controlled, (4) the overlay process of two droplets can be monitored in-situ along the coagulation process. We will use the double optical tweezers to study the detail coagulation process between two droplets, one droplet and one solid particle, and two solid particles in order to understand the process of aerosol from external mixing to internal mixing state.

英文关键词： Raman spectroscopy;optical tweezers;aerosols;coagulation