Non-thermal Surface Chemistry of Halogenated Molecules: Giant Electron-induced Enhancements of Negative Ion Desorption

研究电子辐照下卤化烃吸附层中氟和氯阴离子释放的机理是本研究项目的重点，该项目由分析和表面化学项目支持。罗格斯大学（Rutgers University）的西奥多·马迪（Theodore Madey）教授和他的同事正在研究氯氟化碳与水、氨或非极性共吸附剂接触时的物理吸附层中Cl-和F-的增强排放。目前正在进行一系列测量，以阐明这种增加的排放的机制，以及这可能与平流层中臭氧的非均匀化学反应之间的联系。在不同的表面温度、共吸附质极性和入射电子能量条件下，测量了电子激发离子的角分布和能量分布，以提供对离子发射基本表面过程的机理理解。当用低能电子照射被吸附的氯氟烃化合物层时，大量的氯和氟阴离子被解吸。在某些极性共吸附剂如水和氨的存在下，这种排放显著增强。本研究项目通过一系列离子角和能量分布测量来检验这种效应。本研究将这种效应与非均质平流层化学中的臭氧耗竭问题联系起来。这些研究的结果，除了对地表离子过程提供相当重要的基本见解外，还可能有助于了解平流层臭氧消耗过程

Investigation of the mechanism of fluorine and chlorine anion emission from adsorbed layers of halogenated hydrocarbons irradiated by electrons forms the focus of this research project supported by the Analytical and Surface Chemistry Program. Professor Theodore Madey and his coworkers at Rutgers University are examining the enhanced emission of Cl- and F- from physisorbed layers of CFC's in contact with water, ammonia, or non-polar co-adsorbates. A series of measurements is being carried out to elucidate the mechanism of this enhanced emission, and the connection this may have to the heterogeneous chemistry of ozone in the stratosphere. Electron stimulated ion angular and energy distributions are measured under a variety of conditions of surface temperature, co-adsorbate polarity, and incident electron energy in order to provide mechanistic understanding of the fundamental surface processes of ion emission.When adsorbed layers of chlorofluorocarbon compounds are irradiated with low energy electrons, significant amounts of chlorine and fluorine anions are desorbed. In the presence of certain polar co-adsorbates such as water and ammonia, this emission is dramatically enhanced. This research project examines this effect with a series of ion angular and energy distribution measurements. Connections of this effect with problems of ozone depletion in heterogeneous stratospheric chemistry are made in this research. The results of these studies, in addition to providing considerable fundamental insight into ion processes at surfaces, may help to understand stratospheric ozone depletion processes