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

化学系的化学结构、动力学和机理（CSDM-A）计划将资助加州大学戴维斯分校的吴卓耀教授进行实验研究，研究分子离子和中性分子之间的反应。 在这些实验中，Ng教授和他的团队将改变离子的内能（改变其旋转和振动能量），以了解这如何影响化学反应性。 Ng实验室的大量本科生是该奖项的一个显着因素。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，为他们将来从事研究工作或成为熟练的技术人员做好准备。吴卓耀教授及其研究小组将使用高功率、窄带宽激光器产生真空紫外光谱区的短波长辐射。 这种辐射将用于在分子束中产生特定旋转电子态的分子离子（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，具有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截面和分支比，包括氢气、甲醇、甲烷、氨、乙炔、乙烯、丙烷、丁二炔、氰化氢和水。这些反应在行星上层大气的化学和彗星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.