Time-Resolved Aerosol Collector for CCSEM/EDX Single-Particle Analysis
Time-Resolved Aerosol Collector for CCSEM/EDX Single-Particle Analysis
复制标题
用于 CCSEM/EDX 单颗粒分析的时间分辨气溶胶收集器
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
J. Cowin
中科院分区：
文献类型：
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作者：
A. Laskin;M. Iedema;J. Cowin
研制了一种自动化的时间分辨气溶胶收集器（TRAC），用于对现场收集的气溶胶进行连续采样，用于基于实验室的计算机控制扫描电子显微镜/能量分散X射线（CCSEM/EDX）单粒子分析。收集器被优化为使用网格支撑的50纳米碳膜作为沉积基板。碳膜具有足够低的X射线背景，以允许EDX分析低至0.1-0.2 μ m的颗粒，包括检测低Z元素：C、N和O。TRAC提供无人值守的采样到一组151个单独的网格，在连续的时间间隔短至1分钟。收集后，样品被密封和冷藏等待分析。TRAC-CCSEM/EDX方法的效用是举例说明使用在得克萨斯州2000年空气质量研究（2000年8月15日至9月15日）收集的气溶胶样品。我们能够遵循的时间演变的相对贡献的非挥发性颗粒，如硫酸铵，矿物粉尘，海盐，和含碳的气溶胶化妆。结果显示，除其他事项外，在外观上的细微的碳质和硫酸铵颗粒和大量的混合/涂层的矿物颗粒与硫酸铵的昼夜周期。
An automated Time-Resolved Aerosol Collector (TRAC) has been developed for sequential sampling of field-collected aerosols for laboratory-based Computer Controlled Scanning Electron Microscopy/Energy Dispersed X-ray (CCSEM/EDX) single-particle analysis. The collector is optimized for the use of grid-supported 50 nm carbon films as deposition substrates. The carbon films have low enough X-ray background to permit EDX analysis down to 0.1-0.2 w m particles, including detection of low-Z elements: C, N, and O. The TRAC provides unattended sampling onto a set of 151 individual grids, at sequential time intervals as short as 1 min. After collection, the samples are sealed and refrigerated pending analysis. The utility of the TRAC-CCSEM/EDX approach is exemplified using the aerosol samples collected during the Texas 2000 Air Quality Study (August 15-September 15, 2000). We are able to follow the time evolution in the relative contribution of nonvolatile particles such as ammonium sulfate, mineral dust, sea salt, and carbonaceous in the aerosol makeup. The results show, among other things, the diurnal cycles in appearance of fine carbonaceous and ammonium sulfate particles and substantial mixing/coating of mineral particles with ammonium sulfates.