Spinning Molecules Into Reactive States with an Optical Centrifuge

马里兰大学的Amy Mullin教授在化学结构、动力学和机制项目的支持下，在光学离心机中进行了研究，阐明了分子在极高旋转状态下的结构和行为。光学离心机是基于组合的超快激光脉冲来捕获分子并将其旋转成具有大量角动量的状态，在某些情况下超过了化学键能。离心分子的行为将被询问使用高分辨率状态分辨瞬态红外吸收光谱。项目计划是：(1)测量经过冷却碰撞的二氧化碳分子的能量损失动力学，(2)在光学离心机中对二氧化碳进行光谱研究，以发现大量角动量如何影响化学键的长度和分子的形状，(3)表征在光学离心机中激发的分子的初始量子态分布。(4)探索使用光场捕获分子时如何填充磁亚能级；(5)测试新分子作为光学离心机研究的候选分子。光学离心机是一种令人兴奋和强大的新方法，用于在以前未开发的区域（非常高的旋转状态）制备分子。这些研究代表了化学动力学的一个新前沿，并有可能影响许多科学和技术领域。空间控制分子旋转运动的能力为开发新型化学和获得微观能量下分子运动、结构和能量的新见解打开了大门。高能分子是等离子体、燃烧和大气化学等高温环境中的重要物质。在这项研究中获得的基本见解可能会导致这些领域更清洁，更有效和更安全的应用。在培养研究生的同时，该项目为本科生和高中教师提供了直接参与最先进科学研究的重要机会。

Professor Amy Mullin of the University of Maryland is supported by the Chemical Structure, Dynamics and Mechanisms Program to carry out studies to elucidate the structure and behavior of molecules in extremely high rotational states in an optical centrifuge. The optical centrifuge is based on combined ultrafast laser pulses that trap molecules and spin them into states with large amounts of angular momentum, in some cases exceeding the chemical bond energy. The behavior of the centrifuged molecules will be interrogated using high-resolution state-resolved transient IR absorption spectroscopy. Project plans are to (1) measure the energy loss dynamics of centrifuged carbon dioxide molecules as they undergo cooling collisions, (2) perform spectroscopic studies of carbon dioxide in the optical centrifuge to discover how large amounts of angular momentum affect the length of chemical bonds and the shape of the molecules, (3) characterize the initial quantum state distribution of molecules excited in the optical centrifuge, (4) explore how magnetic sub-levels are populated when using optical fields to trap molecules, and (5) test new molecules as candidates for optical centrifuge studies.The optical centrifuge is an exciting and powerful new method for preparing molecules in a previously unexplored region, that of very high rotational states. The studies represent a new frontier in chemical dynamics and have the potential to impact many areas of science and technology. The ability to spatially control the rotational motion of molecules opens the door for developing new types of chemistry and gaining new insights into molecular motion, structure and energy at a microscopic energy. High energy molecules are important species in high temperature environments, such as plasmas, combustion and atmospheric chemistry. The fundamental insights to be gained in this research may lead to cleaner, more efficient, and safer applications in these areas. Along with the education of graduate students, this project gives undergraduates and high school teachers important opportunities to participate directly in the state-of-the-art scientific research.