Size-selective Spectroscopic Studies of the Geometries, Intermolecular Vibrations and Intermolecular Potential Energy Surfaces of Molecular Clusters

在化学系实验物理化学计划的这个项目中，加州大学洛杉矶分校的Peter Felker将继续他对大的中性分子团簇的结构和分子间势能面的光谱研究。这项工作依赖于旋转相干光谱(RCS)技术，这是费尔克在加州大学洛杉矶分校的实验室帮助开发的。新的研究包括增加质量选择和电离探测拉曼光谱，与纽约大学的兹拉特科·巴西奇教授合作对势能面进行全量子多维计算，并检查非常大的星系团尺寸(在某些情况下，超过20个部分)。我们将获得有关大团簇的几何结构、势能面和振动动力学的信息。通过将气相中的分子以适当的频率暴露在短而尖锐的激光脉冲中，Felker教授可以获得关于相对较少的、可控数量的相互作用分子的几何结构的信息。这些信息对于理解分子在各种化学反应的初始阶段的行为非常有用。此外，自然界中也存在分子团簇，如大气中以及燃烧火焰中。因此，这些实验将提供与大气和燃烧过程有关的信息，并将允许对各种分子间相互作用理论进行测试。最终，人们将对与环境或生物等领域相关的化学意义重大的系统有更详细的了解。

In this project in the Experimental Physical Chemistry Program in the Chemistry Division, Peter Felker of UCLA will continue his spectroscopic studies of the structures and intermolecular potential energy surfaces of large neutral molecular clusters. This work relies on the technique of rotational coherence spectroscopy (RCS) which Felker helped develop in his lab at UCLA. The new studies include the addition of mass selection and ionization-detected Raman spectroscopy, fully quantum multidimensional calculations of potential energy surface via a collaboration with Prof. Zlatko Bacic of NYU, and examining very large cluster sizes (in some cases, greater than 20 moieties). Information will be obtained on geometries, potential energy surfaces, and the vibrational dynamics of the large clusters. %%% By exposing molecules in the gas phase to short, sharp pulses of laser light at the proper frequency, Prof. Felker can obtain information about the geometric structures of a relatively small, controlled number of interacting molecules. This information is very useful for understanding how molecules behave in the initial stages of a wide variety of chemical reactions. In addition, molecular clusters also exist in nature, such as in the atmosphere as well as in combustion flames. These experiments will thus provide information relevant to atmospheric as well as combustive processes and will also permit tests of various theories of intermolecular interaction. Ultimately a more detailed understanding of chemically significant systems will emerge which is relevant to areas such as the environment or biology.