Collaborative Research: Effects of Atmospheric Aging on the Surface vs. Bulk Composition of Atmospheric Organic Aerosol

化学部的环境化学科学计划支持麻省理工学院的杰西·H·克罗尔教授在实验室研究空气-颗粒界面上存在的有机化合物与大部分颗粒中发现的有机化合物之间的化学差异。正在研究和开发用于实时测量表面成分的新的分析技术；其中包括烟尘颗粒气溶胶质谱仪(SP-AMS，一种基于激光的技术，用于快速蒸发含黑碳或金属核心的颗粒)、可调真空紫外光电离(VUV，一种软电离技术)和实时直接分析(DART，一种测量材料表面的质谱学技术)的组合。这些最先进的技术随后将用于环境室内研究，研究次级物种的冷凝如何影响有机气溶胶成分，重点是各种气溶胶成分之间的混合程度和速度。这项研究有望为大气有机细颗粒物的形成和演化提供新的见解。对这些颗粒内的化学梯度和混合的直接检查将对它们的大气行为、反应性和命运提供重要的限制，并最终对它们在全球气候和人类健康中的作用提供重要的限制。

The Environmental Chemical Sciences Program in the Chemistry Division supports Professor Jesse H. Kroll of the Massachusetts Institute of Technology for the laboratory study of chemical differences between organic compounds present at the air-particle interface and those found within the bulk of the particles. New analytical techniques for the real-time measurement of the surface composition are being investigated and developed; these include combinations of soot particle aerosol mass spectrometry (SP-AMS, a laser-based technique for the rapid vaporization of particles containing black carbon or metal cores), tunable vacuum ultraviolet photoionization (VUV, a soft ionization technique), and direct analysis in real time (DART, a mass spectrometric technique for the measurement of material surfaces). These state-of-the-art techniques will then be used in environmental chamber studies, examining how the condensation of secondary species affect organic aerosol composition, with a focus on the extent and rate of mixing between various aerosol components. This study is expected to provide new insights into the formation and evolution of atmospheric organic fine particles. The direct examination of chemical gradients and mixing within such particles will provide important constraints on their atmospheric behavior, reactivity, and fate, and ultimately on their role in global climate and human health.