Nesbitt David J, Zolot Alex M, Roscioli Joseph R, Ryazanov Mikhail
JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.
Department of Physics, University of Colorado, Boulder, Colorado 80309, United States.
Acc Chem Res. 2023 Mar 21;56(6):700-711. doi: 10.1021/acs.accounts.2c00823. Epub 2023 Feb 27.
ConspectusWe often teach or are taught in our freshman courses that there are three phases of matter─gas, liquid and solid─where the ordering reflects increasing complexity and strength of interaction between the molecular constituents. But arguably there is also a fascinating additional "phase" of matter associated with the microscopically thin interface (<10 molecules thick) the gas and liquid, which is still poorly understood and yet plays a crucial role in fields ranging from chemistry of the marine boundary layer and atmospheric chemistry of aerosols to the passage of O and CO through alveolar sacs in our lungs. The work in this Account provides insights into three challenging new directions for the field, each embracing a rovibronically quantum-state-resolved perspective. Specifically, we exploit the powerful tools of chemical physics and laser spectroscopy to pose two fundamental questions. (i) At the microscopic level, do molecules in all internal quantum-states (e.g., vibrational, rotational, electronic) colliding with the interface "stick" with unit probability? (ii) Can reactive, scattering, and/or evaporating molecules at the gas-liquid interface avoid collisions with other species and thereby be observed in a truly "nascent" collision-free distribution of internal degrees of freedom? To help address these questions, we present studies in three different areas: (i) reactive scattering dynamics of F atoms with wetted-wheel gas-liquid interfaces, (ii) inelastic scattering of HCl from self-assembled monolayers (SAMs) via resonance-enhanced photoionization (REMPI)/velocity map imaging (VMI) methods, and (iii) quantum-state-resolved evaporation dynamics of NO at the gas-water interface. As a recurring theme, we find that molecular projectiles reactively, inelastically, or evaporatively scatter from the gas-liquid interface into internal quantum-state distributions with respect to the bulk liquid temperatures (). By detailed balance considerations, the data unambiguously indicate that even simple molecules exhibit rovibronic state dependences to how they "stick" to and eventually solvate into the gas-liquid interface. Such results serve to underscore the importance of in energy transfer and chemical reactions at the gas-liquid interface. This nonequilibrium behavior may well make this rapidly emergent field of chemical dynamics at gas-liquid interfaces more complicated but even more interesting targets for further experimental/theoretical exploration.
概述
在我们的新生课程中，我们经常讲授或被讲授物质有三个相——气体、液体和固体——其中分子组成部分之间的有序性反映了相互作用的复杂性和强度不断增加。但可以说，物质还有一个迷人的额外“相”，与气体和液体之间微观上很薄的界面（<10个分子厚）相关，这个界面仍然知之甚少，但在从海洋边界层化学和气溶胶大气化学到氧气和二氧化碳在我们肺部肺泡囊中通过等领域都起着至关重要的作用。本综述文章中的工作为该领域提供了三个具有挑战性的新方向的见解，每个方向都采用了振转电子量子态分辨的视角。具体来说，我们利用化学物理和激光光谱的强大工具提出两个基本问题。（i）在微观层面上，所有内部量子态（例如振动、转动、电子态）的分子与界面碰撞时，是否以单位概率“附着”？（ii）气液界面处的反应性、散射性和/或蒸发性分子能否避免与其他物种碰撞，从而在真正“新生”的内部自由度无碰撞分布中被观测到？为了帮助回答这些问题，我们展示了在三个不同领域的研究：（i）F原子与湿轮气液界面的反应性散射动力学，（ii）通过共振增强光电离（REMPI）/速度映射成像（VMI）方法研究HCl从自组装单分子层（SAMs）的非弹性散射，以及（iii）气水界面处NO的量子态分辨蒸发动力学。作为一个反复出现的主题，我们发现分子抛射体从气液界面发生反应性、非弹性或蒸发性散射，进入相对于本体液体温度（）的内部量子态分布。通过细致平衡的考虑，数据明确表明，即使是简单分子，其“附着”并最终溶剂化到气液界面的方式也表现出振转电子态依赖性。这些结果强调了在气液界面能量转移和化学反应中的重要性。这种非平衡行为很可能使气液界面处这个迅速兴起的化学动力学领域变得更加复杂，但同时也是进一步进行实验/理论探索的更有趣的目标。
