Analysis of Brominated Compounds in the Atmosphere by the Photodetachment-Modulated Electron Capture Detector

近年来，人们日益认识到，大气中的溴化化合物（BrC’s）可能在平流层臭氧消耗中发挥重要作用，特别是在南极和北极地区。迄今为止，关于平流层臭氧消耗的大部分注意力都集中在氯化化合物（ClC’s）的作用上，部分原因是它们在对流层中的浓度相对较高，现在总量远远超过十亿分之一（摩尔比）。与BrC的大气研究相关的最大挑战之一是它们在对流层中的浓度相对较低，通常在低或万亿分之一的范围内。因此，在大气样品中检测和定量分析BrC相对困难，因为大气样品中总是含有大量过量的其他有机化合物，包括ClC。在本研究中，一种新的仪器将被应用于大气样品中BrC的分析。该仪器被称为sif4掺杂光分离-调制电子捕获检测器（SiF4-PDMECD），并已被证明对BrC提供敏感响应，但对ClC或其他有机化合物没有响应。在这个项目中，SiF4-PDMECD将被专门用于大气中BrC的分析，从而为大气化学领域的未来溴化化合物的大气化学研究提供额外的，很可能是优越的分析能力。

In recent years it has become increasingly recognized that brominated compounds (BrC's) in the atmosphere may play a significant role in stratospheric ozone depletion, especially in the Antarctic and Arctic regions. Most of the attention, to date, concerning stratospheric ozone depletion has centered on the role of chlorinated compounds (ClC's), due in part to their relatively high concentrations in the troposphere, now totaling well over a part per billion (mole ratio). One of the greatest challenges associated with atmospheric studies of the BrC's is related to their relatively low concentrations in the troposphere, typically in the low or sub parts per trillion range. The BrC's are therefore relatively difficult to detect and quantitatively analyze in atmospheric samples that invariably contain a large excess of other organic compounds, including the ClC's. In this research, a new instrument, will be applied to the analysis of BrC's in atmospheric samples. This instrument is called the SiF4-doped Photodetachment-Modulated Electron Capture Detector (SiF4-PDMECD) and has been shown to provide sensitive responses to BrC's, but does not respond to ClC's or other organic compounds. In this project, the SiF4-PDMECD will be evaluated specifically for the analysis of BrC's in the atmosphere and will thereby provide the field of atmospheric chemistry with an additional and very possibly a superior analysis capability for future investigations of the atmospheric chemistry of brominated compounds.