Collaborative Research: Evolution and Impact of Aerosol Phase and Morphology

该项目包括实验和模拟研究，以调查大气中小颗粒形成和老化期间发生的过程。微小的有机颗粒可以分解成液体，然后可以改变大气的后续化学成分。将通过实验研究颗粒的大小、形状和组成等特性对颗粒相分离的影响。模型将被用来研究这些颗粒对大气的影响。该项目的假设是液-液相分离(LLP)过程由颗粒的分子组成和颗粒尺寸决定。这一假设将通过流动反应器中α-Pine的暗臭氧分解和1，2，4-三甲苯的光氧化产生的二次有机气溶胶(SOA)来验证。将收集颗粒，并用低温透射电子显微镜分析它们的形态。该提案将解决的研究问题如下：(1)颗粒级参数(O：C、有机：硫酸盐比、粒度等)是什么？决定颗粒形态？(2)气溶胶颗粒形态是如何随时间演变的？具体地说，颗粒的大小和老化如何影响颗粒的形态？以及(3)气溶胶形态对气溶胶过程的影响是什么，例如非均相N2O5的水解？粒子分辨建模框架将利用实验结果并将其整合，以量化发现与大气化学的相关性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project includes both experimental and modeling studies to investigate processes that occur during the formation and aging of small particles in the atmosphere. Small organic particles can separate into liquid phases that then can change the subsequent chemistry of the atmosphere. Experiments will be conducted to study how particle properties such as size, shape, and composition affect particle phase separation. Models will be used to study the impacts these particles have on the atmosphere.The hypothesis of the project is that the liquid-liquid phase separation (LLPS) process is governed by the molecular composition of the particle and the particle size. This hypothesis will be tested using secondary organic aerosol (SOA) produced from the dark ozonolysis of alpha-pined and the photooxidation of 1,2,4-trimethylbenzene in a flow reactor. Particles will be collected, and their morphology will be analyzed by cryotransmission electron microscopy. The research questions that will be addressed by the proposal are the following: (1) What particle-level parameters (O:C, organic:sulfate ratio, size, etc.) determine particle morphology? (2) How does the morphology of aerosol particles evolve in time? Specifically, how do the size of particles and aging influence particle morphology? and (3) What is the impact of aerosol morphology on aerosol processes such as heterogeneous N2O5 hydrolysis? A particle-resolved modeling framework will make use of the experimental results and integrate them to quantify the relevance of the findings for atmospheric chemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.