Surface Enrichment in Nanodroplet Aerosols

Barbara Wyslouzil得到了理论与计算化学项目的资助，继续她对气溶胶粒子成核的实验研究。本文的目标是利用小角中子散射（SANS）来寻找气溶胶中多组分纳米级液滴的结构。Wyslouzil将寻找多组分液滴的表面富集，她预计这些液滴具有纳米尺度的内部结构。她已经完善了一种超音速喷嘴的设计，可以产生均匀大小的气溶胶液滴，并测试了使用SANS进行深度剖面实验的可行性。在该研究计划的下一阶段，Wyslouzil计划解决三个任务：1)对二元纳米液滴进行实验，以确定其组成和结构；2)提高她对气溶胶进行SANS测量的能力；3)完善数据分析程序和建模，以解释SANS实验数据。在许多工业和自然环境中，多组分的纳米级气溶胶粒子是由成核和冷凝产生的。细耐火颗粒在燃烧和冶金过程中形成，而硫酸-水滴在烟囱气体、火山烟雾中产生，并作为大气中光化学反应的副产品。这些颗粒的表面组成可以强烈地影响非均相反应、生长和蒸发动力学以及微量气体的调节。Wyslouzil的研究将有助于我们对这种现象的基本理解。

Barbara Wyslouzil is supported by a grant from the Theoretical and Computational Chemistry Program to continue her experimental research on nucleation of aerosol particles. The goal of the proposed work is to use small angle neutron scattering (SANS) to look for structure in multicomponent nanometer sized liquid droplets in an aerosol. Wyslouzil will be looking for surface enrichment in multicomponent droplets which she anticipates have internal structures on the nanometer length scale. She has already perfected a supersonic nozzle design that produces aerosol droplets of uniform size and has tested the feasibility of using SANS for performing depth profiling experiments. During the next phase of this research program, Wyslouzil plans to address three tasks: 1) conduct experiments with binary nanodroplets to determine their composition and structure; 2) improve her ability to conduct SANS measurements from aerosols; and 3) refine the data analysis procedures and modeling for interpreting the SANS experimental data. Multicomponent, nanometer-sized aerosol particles are produced by nucleation and condensation in many industrial and natural settings. Fine refractory particles form in combustion and metallurgical processes while sulfuric acid - water droplets are produced in stack gases, volcanic plumes, and as a byproduct of photochemical reactions in the atmosphere. The surface composition of these particles can strongly affect heterogeneous reactions, growth and evaporation kinetics, and the accomodation of trace gaseous species. Wyslouzil's research will contribute to our basic understanding of such phenomena.