The dynamics of heterogeneous reactions at ice surfaces relevant to atmospheric, interstellar and hypergolic phenomena.

与大气、星际和自转现象相关的冰表面异质反应动力学。

• 批准号: RGPIN-2022-04602
• 负责人: Ayotte, Patrick
• 金额: $ 2.11万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748648
• 关键词: dynamics; heterogeneous; reactions; ice; surfaces

The investigations described in this proposal rely on the preparation of metastable species using molecular beam techniques to study interfacial chemical dynamics of key heterogeneous atmospheric, hypergolic, and interstellar chemistry reactions. The first theme will exploit a recently developed methodology to prepare trans-ONONO2, a metastable isomer of the nitrogen dioxide dimer that was proposed to be a key reaction intermediate for NO2 hydrolysis, but also for prototypical hypergolic reactions with hydrazine, H2NNH2. These important reactions will be investigated within amorphous solid water/hydrazine, and at their surface, at temperatures where reaction intermediates can be trapped and characterized spectroscopically by exploiting electric field standing waves (EFSW) to enhance the specificity and sensitivity of reflection-absorption IR spectroscopy (RAIRS) providing valuable molecular-level insight into reaction mechanisms and their dynamics. Custom instrumentation will also be developed to allow for these investigations to be performed under environmentally relevant conditions while field studies of the photochemical NOx fluxes at the Canadian High Arctic Research Station (CHARS) will also be initiated. The second theme aims at improving our understanding of confinement effects on the interconversion between ortho and para nuclear spin isomers (NSI) of small molecules (H2O, NH3, C2H2, and H2CO) for magnetic resonance applications in surface science. The proposed investigations build upon our unique capabilities for the preparation of beams of these small molecules enriched in their metastable ortho NSI using magnetic focusing thereby allowing state-to-state NSI interconversion dynamics upon scattering at surfaces to be performed by resonance-enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOF-MS). As confinement of NSI upon their adsorption at surfaces triggers their interconversion, the erosion of the enrichment in their ortho NSI hampers potential magnetic resonance applications to surface science relying on spin polarized molecules. Confinement effects will also be investigated in endofullerenes as recent work showed that the ro-translational dynamics could yield very slow erosion in the NSI distributions of D216O@C60 as the confinement-induced inter- and inter-molecular couplings responsible for NSI interconversion may be strongly suppressed in these compounds.  Materials with enhanced retention of their nuclear spin isomers are highly desirable and could find applications in magnetic resonance spectroscopy and imaging as well as quantum information processing.  These two research themes will provide ample opportunities for HQP to be trained in advanced custom experimental, numerical simulations, and molecular modelling methods of molecular sciences, in a highly collaborative environment, that involves industrial and academic partners from around the world.

本提案中描述的调查依赖于使用分子束技术制备亚稳物种，以研究关键的非均质大气，自燃和星际化学反应的界面化学动力学。第一个主题将利用最近开发的方法来制备trans-ONONO 2，二氧化氮二聚体的亚稳异构体，被认为是NO2水解的关键反应中间体，也是与肼H2 NNH 2的典型自燃反应。这些重要的反应将在无定形固体水/肼内进行研究，并在它们的表面，在反应中间体可以被捕获的温度下，并通过利用电场驻波（EFSW）进行光谱表征，以提高反射吸收红外光谱（RAIRS）的特异性和灵敏度，从而为反应机制及其动力学提供有价值的分子水平的洞察力。还将开发定制仪器，以便在与环境有关的条件下进行这些调查，同时还将开始在加拿大高北极研究站对光化学氮氧化物通量进行实地研究。第二个主题的目的是提高我们的理解的限制效应之间的相互转换的邻位和帕拉核自旋异构体（NSI）的小分子（H2O，NH3，C2 H2，和H2 CO）的磁共振应用在表面科学。拟议的研究建立在我们使用磁聚焦制备富含亚稳态邻位NSI的这些小分子束的独特能力之上，从而允许通过共振增强多光子电离进行表面散射时的状态与状态NSI相互转换动力学飞行时间质谱（REMPI-TOF-MS）。由于NSI在其表面吸附后的限制触发了它们的相互转化，因此其邻位NSI中富集的侵蚀阻碍了依赖于自旋极化分子的表面科学的潜在磁共振应用。限制效应也将在内嵌富勒烯中进行研究，因为最近的工作表明，由于限制诱导的相互作用和相互作用，在这些化合物中，负责NSI互变的分子偶联可以被强烈抑制。磁共振光谱和成像以及量子信息处理。这两个研究主题将为HQP提供充足的机会，在高度合作的环境中，包括来自世界各地的工业和学术合作伙伴，在分子科学的高级定制实验，数值模拟和分子建模方法方面进行培训。