ICE Chemistry And Physics: Astrophysics, Dynamics and Environment (ICECAPADE)

ICE 化学和物理：天体物理学、动力学和环境 (ICECAPADE)

• 批准号: RGPIN-2017-05395
• 负责人: Ayotte, Patrick
• 金额: $ 2.04万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710827
• 关键词: ICE; Chemistry; Physics; Astrophysics; Dynamics

Innovative applications of molecular beam methods will be deployed to study elementary heterogeneous (photo)chemical processes on ice surfaces which are of interest to develop molecular-level interpretations for astrophysical phenomena in the interstellar medium, for fundamental interfacial chemical dynamics and for atmospheric chemistry processes relevant to the polar boundary layer. We propose to use a novel methodology based on a recently developed magnetically focused molecular beam source, enabling the production of water vapor highly enriched in the ortho-H2O nuclear spin isomers, to devise and optimize separation strategies and the transfer of ortho-H2O, and of the resulting spin polarisation, to the condensed phase and surfaces. Confinement effects are germane to any storage methodologies therefore, we propose to perform systematic studies of nuclear spin conversion that will shed light on intra- and inter-molecular contributions to the underlying mechanism. This may contribute to improve storage strategies thereby extending the lifetime of condensed phase water samples enriched in ortho-H2O. These methodological developments will set the stage for fundamental interfacial chemical dynamics, heterogeneous catalysis of nuclear spin conversion and important NMR spectroscopy applications as well as for laboratory studies of the behavior of the nuclear spin isomers of water observed in comae and protoplanetary disks. Photochemical processes are often enhanced in molecules adsorbed onto ice surfaces due to their peculiar solvation environment. We will use thin amorphous solid water films as surrogates for the quasi-liquid layer that resides at the ice surface in the natural environment and study the surface specificity of elementary processes responsible for intense NOx photochemical fluxes that emanate from the sunlit snowpack to the boundary layer upon polar Spring. Using our molecular beam/surface spectroscopy and kinetics methodology, as well as ultrafast spectroscopic techniques, we will investigate heterogeneous NO2 hydrolysis and photolysis in/on condensed water and provide improved mechanistic descriptions and quantitative kinetic parameters. This will advance kinetic modelling efforts of the complex coupled kinetics involved in this important natural phenomenon. Finally, environmental cryogenic electron microscopy studies of the heterogeneous nucleation and growth of ice will reveal the role played by substrate properties and growth conditions on the structure and morphology of thin vapor-deposited ice films which contribute to the interpretation of our spectroscopic/kinetics work. They will be pursued in concert within our FQR-NT funded project, sponsored by industrial partner Rio Tinto-Alcan International Limited, on the mitigation of mineral dust emissions at the Site de Disposition des Résidus de Bauxite, Jonquière, Qc.

将利用分子束方法的创新应用来研究冰表面上的基本非均相(光)化学过程，这对于发展对星际介质中的天体物理现象、基本界面化学动力学和与极地边界层有关的大气化学过程的分子水平的解释是有意义的。 我们建议使用一种基于最近开发的磁聚焦分子束源的新方法，能够产生高度富含邻位-H2O核自旋异构体的水蒸气，以设计和优化分离策略，并将邻位-H2O以及由此产生的自旋极化转移到凝聚相和表面。限制效应与任何存储方法都是密切相关的，因此，我们建议对核自旋转换进行系统的研究，以揭示分子内和分子间对潜在机制的贡献。这可能有助于改进储存策略，从而延长富含邻位水的冷凝相水样的寿命。这些方法学的发展将为基本的界面化学动力学、核自旋转换的非均相催化和重要的核磁共振波谱应用以及在大气层和原行星盘中观察到的水的核自旋异构体的行为的实验室研究奠定基础。 由于其特殊的溶剂化环境，吸附在冰表面上的分子的光化学过程经常被加强。我们将用薄的无定形固体水膜代替自然环境中冰表面的准液态层，并研究极地春季从阳光照耀的积雪向边界层发出的强烈NOx光化学通量的基本过程的表面特异性。使用我们的分子束/表面光谱和动力学方法，以及超快光谱技术，我们将研究NO2在冷凝水中的非均相水解和光解，并提供改进的机理描述和定量动力学参数。这将推进涉及这一重要自然现象的复杂耦合动力学的动力学建模工作。 最后，环境低温电子显微镜对冰的非均相成核和生长的研究将揭示衬底性质和生长条件对气相沉积的薄冰膜的结构和形貌所起的作用，这有助于解释我们的光谱/动力学工作。它们将在我们的FQR-NT资助项目中协调实施，该项目由工业合作伙伴力拓-阿尔坎国际有限公司赞助，旨在减少昆士兰容基耶尔铝土矿现场的矿物粉尘排放。