Imaging collisions of OH radicals with liquid surfaces

这是一个化学博士研究项目。气相分子与液体表面的相互作用在许多现实环境中是重要的。他们的研究提出了一些严重的实验挑战，因为开发可以与液相样品相结合的表面敏感方法的困难。这些反应中的一个重要类别是在大气气溶胶颗粒表面吸收OH自由基;这些过程具有重要的气候影响。我们一直在研究OH自由基与液体表面碰撞中的基本初级事件，选择液体表面作为气溶胶表面化学功能的代理。我们通过引入OH自由基的分子束源并将其与一种新颖的基于激光的成像方法相结合，扩展了我们以前的工作。这为进行新的动力学测量开辟了道路，在那里我们可以获得散射OH分子的速度和角分布与其内部量子态之间的相关性。所观察到的特征高度表明了在表面竞争的直接和更复杂的碰撞机制之间的平衡。这种见解是有价值的，无论是在这个特定的背景下，也有助于更广泛地告知气液界面化学的一般领域。

This is a PhD research project in Chemistry. The interactions of gas-phase molecules with the surfaces of liquids are important in a number of real-world environments. Their study presents a number of serious experimental challenges, because of the difficulties of developing surface-sensitive methods that can be coupled with liquid-phase samples. One important class of these reactions is the uptake of OH radicals at the surfaces of atmospheric aerosol particles; these processes have important climatic implications. We have been studying the fundamental primary events in the collisions of OH radicals with liquid surfaces chosen as proxies for the chemical functionality present at the surfaces of aerosols. We have extended our previous work by introducing a molecular-beam source of the OH radicals and combining it with a novel, laser-based imaging method. This has opened the way to making new classes of dynamical measurements, where we can obtain the correlations between the speed and angular distributions of the scattered OH molecules and their internal quantum states. The observed characteristics are highly indicative of the balance between competing direct and more-complex collisional mechanisms at the surface. This insight is valuable, both in this particular context and also in helping to inform the general field of gas-liquid interfacial chemistry more widely.