State-selected ion-molecule reactions of relevance to planetary atmospheres and cometary comae

化学系的化学结构、动力学及机理（CSDM-A）计划获此资助，资助加州大学戴维斯分校吴卓耀教授进行分子离子与中性分子之间反应的实验研究。在这些实验中，吴教授和他的团队将改变离子的内能（改变其旋转和振动能），以观察这如何影响化学反应性。吴恩达实验室的大量本科生是该奖项的一个值得注意的因素。参与该项目的研究生和本科生将接受激光科学、光学和真空方法以及光谱学方面的技术培训，为他们从事研究工作或进入熟练的技术劳动力做好准备。吴卓耀和他的研究小组将使用高功率、窄频宽的激光器，在真空紫外光谱区产生短波长的辐射。这种辐射将被用来在分子束中产生具有特定振动状态的分子离子（氮、水、氧、一氧化碳和二氧化碳+1阳离子）。其他科学家过去的工作表明，不同振动和旋转能量的分子的反应性差异很大，但对分子离子的反应性差异知之甚少。将测量各种碰撞伙伴的总横截面和分支比，包括氢、甲醇、甲烷、氨、乙炔、乙烯、丙烷、二乙炔、氰化氢和水。这些反应在行星上层大气的化学和彗星的化学中都很重要。

With this award, the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program of the Division of Chemistry is funding Professor Cheuk-Yiu Ng of the University of California-Davis to conduct experimental studies to look at the reactions between molecular ions and neutral molecules. In these experiments, Professor Ng and his group will vary the internal energy of the ion (changing its rotational and vibrational energy) to see how this effects the chemical reactivity. The inclusion of a large number of undergraduates in the Ng laboratory is a notable element of this award. The graduate and undergraduate students working on this project will receive technical training in laser science, optical and vacuum methods, and spectroscopy, preparing them for research careers or entry into the skilled technical workforce.Prof. Cheuk-Yiu Ng and his research group will use high power, narrow-bandwidth lasers to generate short-wavelength radiation in the vacuum ultraviolet (VUV) spectral region. This radiation will be used to produce molecular ions (nitrogen, water, oxygen carbon monoxide and carbon dioxide +1 cations) in specific rovibronic states in a molecular beam. Past work by other scientists has shown profound reactivity differences for molecules with varying amounts of vibrational and rotational energy, but relatively little is known about reactivity differences in molecular ions. The total cross section and branching ratios will be measured for a variety of collision partners, including hydrogen, methanol, methane, ammonia, acetylene, ethylene, propane, diacetylene, hydrogen cyanide and water. These reactions are important in the chemistry of the upper atmospheres of planets as well as in the chemistry of cometary comae.