Interfacial specificity of heterogeneous atmospheric and interstellar chemistry on ice/Spécificité interfaciale de la chimie atmosphérique et interstellaire sur la glace

我们的研究计划提供了定量的分子水平的描述冰上的基本非均质过程，以改善我们的描述知之甚少的大气化学和天体物理现象，涉及冰表面。我们的方法依赖于分子束和表面化学技术的组合，与光学和电子光谱学和显微镜相结合，研究复杂的耦合动力学的吸附，解吸和反应的杂质到薄的冰膜，以及它们的吸收和扩散内的散装。通过分子建模和模拟，我们提供了详细的描述界面（光）化学过程如何不同于他们的散装模拟使用实验室模型系统的灵感来自大气化学问题。拟议的工作将提高我们对简单酸分子（HF，HCl，HBr，HNO 3）如何吸附到冰上，它们如何溶解并被吸收到冰中，以及大气化学现象（如平流层臭氧消耗）中的重要基本过程的基本理解。我们还打算巩固最近和正在进行的调查，异质硝酸盐光化学，试图更好地了解源的强烈的光化学氮氧化物通量观察到的极地日出后，从积雪散发到极地边界层。最后，在水的自旋同位素分离的最新进展使我们能够进行一个令人兴奋的新方向的发展：水在基质和冰中的自旋转化化学的研究，以及其均相和多相催化。这个经典的化学物理学问题有望教会我们在星际介质中测量的正-对位比，例如从彗星升华的水分子的正-对位比，与冰的温度以及原始星云的温度是如何相关的。它还将帮助建立实验方案，用于制备和储存o-H2O和p-H2O的高度富集样品，以研究自旋化学如何在涉及不可分辨质子的化学反应中从反应物映射到产物。

Our research program provides quantitative molecular-level descriptions of elementary heterogeneous processes on ice in order to improve our description of poorly understood atmospheric chemistry and astrophysical phenomena involving ice surfaces. Our approach relies on a combination of molecular beam and surface chemistry techniques, in concert with optical and electronic spectroscopy and microscopy, to study the complex coupled kinetics for adsorption, desorption and reaction of impurities onto thin ice films, as well as their absorption and diffusion within the bulk. Through molecular modelling and simulations, we provide detailed descriptions of how interfacial (photo)chemical processes differ from their bulk analogues using laboratory model systems inspired from atmospheric chemistry problems. The proposed work will improve our fundamental understanding of how simple acid molecules (HF, HCl, HBr, HNO3) adsorb onto ice, how they dissolve and become absorbed into ice, important elementary processes in atmospheric chemistry phenomena such as stratopheric ozone depletion. We also intend to consolidate recent and ongoing investigations of heterogeneous nitrates photochemistry in an attempt to better understand the source of the intense photochemical NOx fluxes observed to emanate from the snowpack to the polar boundary layer upon polar sunrise. Finally, recent developments in the separation of spin isotopomers of water poises us to undertake the development of an exciting new direction: studies of spin conversion chemistry of water in matrices and ice as well as its homogeneous and heterogeneous catalysis. This classical chemical physics problem promises to teach us how ortho-para ratios measured in the interstellar medium, such as those of water molecules sublimating from comets, are related to the temperature of the ice and also, of the primordial nebulae. It will also help establish experimental protocol for the preparation and storage of highly enriched samples of o-H2O and p-H2O for the study of how spin chemistry maps from reactants to products in chemical reactions involving indiscernible protons.