Electron-beam Analyses of Individual Particles: Applicationsto Atmospheric Chemistry

这是一个旨在确定北极、北大西洋和赤道太平洋偏远地区对流层气溶胶中单个颗粒的化学和形态特征的项目。行星边界层和对流层中层的这类粒子很重要，因为它们影响太阳辐射平衡、气候稳定以及天然物质和污染物在全球的扩散。分析将用自动电子束仪器进行。过去十年发展起来的方法使人们能够研究大量的颗粒，并确定颗粒的类型、浓度和大小分布。所得数据将用于解决大气气溶胶研究中的当前问题。要研究的是：(a)海洋气溶胶粒子的产生、分馏和反应；(b)生产天然的非海盐硫酸盐颗粒；(c)其他自然和人为粒子类型的来源、运输和命运。自动颗粒分析将使用扫描电子显微镜和电子探针进行。作为第二项任务，复杂亚微米粒子的结构和组成将在高空间分辨率下使用透射电子显微镜，通过成像和化学分析进行研究。这些提议的研究，综合起来，将提供关于化学成分、形态和各种单个粒子内部结构的精细数据。这些数据反过来将为气溶胶颗粒的起源、化学反应、扩散和最终命运提供重要的见解。//

This is a project to determine the chemical and morphological characteristics of individual particles from tropospheric aerosols of remote areas in the Artic, North Atlantic, and Equatorial Pacific. Such particles in the planetary boundary layer and mid-troposphere are important because of their impact on the solar radiation balance, climate stability, and the global dispersion of natural and pollutant material. Analyses will be performed with automated electron- beam instruments. Methods developed over the past decade allow one to study large numbers of particles and to determine particle types, concentrations, and size distributions. The resulting data will be used to address current issues in atmospheric aerosol research. To be investigated are: (a) generation, fractionation, and reactions of marine aerosol particles; (b) production of natural, non-sea-salt sulfate particles; and (c) sources, transport, and fates of other particle types, both natural and anthropogenic. Automated particle analysis will be performed using a scanning electron microscope and an electron microprobe. As a secondary task, the structure and composition of complex submicron particles will be investigated at high spatial resolutions using transmission electron microscopy, both by imaging and by chemical analysis. The proposed studies, taken together, will provide fine-scale data about the chemical compositions, morphologies, and internal structures of a wide variety of individual particles. These data, in turn, will provide important insights into aerosol particle origins, chemical reactions, dispersion, and ultimate fates. //