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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=644356
• 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.*****

分子束方法的创新应用将用于研究冰表面的基本异质（光）化学过程，这对于对星际介质中的天体物理现象、基本界面化学动力学以及与极地边界层相关的大气化学过程进行分子水平的解释很有意义。********我们建议使用一种基于最近开发的磁聚焦的新颖方法。 分子束源，能够产生富含邻水核自旋异构体的水蒸气，设计和优化分离策略以及邻水的转移以及由此产生的自旋极化到凝聚相和表面。限制效应与任何存储方法都密切相关，因此，我们建议对核自旋转换进行系统研究，这将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，从而延长富含原水的凝聚相水样的寿命。 这些方法学的发展将为基础界面化学动力学、核自旋转化的多相催化和重要的核磁共振波谱应用以及在彗发和原行星盘中观察到的水的核自旋异构体行为的实验室研究奠定基础。********由于其特殊的溶剂化作用，吸附在冰表面的分子中的光化学过程通常会得到增强。 环境。 我们将使用薄的无定形固体水膜作为自然环境中冰表面的准液体层的替代品，并研究负责从阳光照射的积雪到极地春天边界层的强烈氮氧化物光化学通量的基本过程的表面特异性。 利用我们的分子束/表面光谱和动力学方法以及超快光谱技术，我们将研究冷凝水中/冷凝水中的非均相 NO2 水解和光解，并提供改进的机理描述和定量动力学参数。 这将推进这一重要自然现象中复杂耦合动力学的动力学建模工作。********最后，对冰的异质成核和生长的环境低温电子显微镜研究将揭示基底特性和生长条件对薄气相沉积冰膜的结构和形态所起的作用，这有助于解释我们的光谱/动力学工作。这些目标将在我们的 FQR-NT 资助项目（由工业合作伙伴 Rio Tinto-Alcan International Limited 赞助）内协调一致地进行，该项目旨在减少魁北克省 Jonquière 铝土矿处置场的矿物粉尘排放。*****