Reactions of Highly Excited Molecules: From Supercollisions to Super-reactions?

波士顿大学的Amy Mullin得到实验物理化学计划的支持，开展旨在阐明气相中高度激发的多原子分子的碰撞和反应过程的行为和基本原理的研究。 实验研究将使用脉冲紫外纳秒吸收，然后快速无辐射衰变，以制备高度振动激发的苯类分子，其内部能量从15，000到45，000波数不等。高分辨率瞬态红外吸收探测将用于监测碰撞伙伴的能量增益或反应产物的外观。 项目计划是：（1）研究激发态奥林中碰撞弛豫的能量依赖性，（2）发现相对较小的激发态分子（如二硫化碳）的内能含量如何影响碰撞猝灭动力学，（3）通过测量氨中的能量增益，探索静电相互作用如何影响高能分子的碰撞弛豫，（4）研究内能在高能分子的氢和氘提取反应中的作用，（5）确定在水和氘化水浴中高能分子的交换反应与碰撞能量转移竞争的方式，以及（6）执行经典轨迹计算以帮助解释实验发现。活化分子在化学和生物化学的几乎每一个层次上都起着重要的作用。 含有大量能量的分子通常是最具反应性的物种，因此对于确定热环境的化学性质是最重要的。这种情况对于涉及大气、等离子体和燃烧化学的高温过程尤其如此。 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，更安全的应用。 沿着研究生教育，该项目为本科生和高中生提供了直接参与最先进科学研究的重要机会。

Amy Mullin of Boston University is supported by the Experimental Physical Chemistry Program to carry out studies aimed at elucidating the behavior and underlying principles that govern collisional and reactive processes of highly excited polyatomic molecules in the gas phase. Experimental studies will use pulsed UV nanosecond absorption, followed by rapid radiationless decay, to prepare highly vibrationally excited benzene-like molecules with internal energies ranging from 15,000 to 45,000 wavenumbers. High-resolution transient infrared absorption probing will be employed to monitor energy gain in collision partners or the appearance of reaction products. Project plans are to (1) investigate the energy dependence of collisional relaxation in excited azulene, (2) discover how internal energy content in relatively small excited molecules such as carbon disulfide influences collisional quenching dynamics, (3) explore how electrostatic interactions influence collisional relaxation of high-energy molecules by measuring energy gain in ammonia, (4) investigate the role of internal energy on hydrogen and deuterium abstraction reactions of high-energy molecules, (5) determine the ways in which exchange reactions of high-energy molecules compete with collisional energy transfer in water and deuterated water baths, and (6) perform classical trajectory calculations to aid in interpreting the experimental findings. Activated molecules play important roles in chemistry and biochemistry at almost every level. Molecules containing large amounts of energy are usually the most reactive species and hence are among the most important for determining the chemistry of thermal environments. This situation is especially true for high temperature processes involved in atmospheric, plasma, and combustion 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 students important opportunities to participate directly in the state-of-the-art scientific research.