PHOtolysis Reaction Mechanisms by Emerging and New Technologies - PhoRMENT

新兴新技术的光解反应机制 - PhoRMENT

• 批准号: 2885177
• 金额: --
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2885177
• 关键词: PHOtolysis; Reaction; Mechanisms; Emerging; New

Photochemistry controls a vast array of the natural and man-made chemical processes: photosynthesis, plasma technology, solar energy, combustion and atmospheric chemistry. An important example is atmospheric photo-oxidation, which drives the atmospheric radical propagation cycles that breakdown primary pollutant emissions, but also controls the formation of secondary pollutants such as ozone and oxygenated volatile organic compounds (VOC), which can have significant impacts on climate, air quality and human health.Despite the clear importance of the subject, experimental limitations have inhibited the study of even the simplest processes by which small gas-phase molecules interact with chemically active ultra violet (UV) light. In this project you will exploit new and emerging technologies such as low cost UV LEDs, chemosensors (developed in York) for sensitive and selective free-radical detection, online mass spectrometry, and modern theoretical computational methods to study atmospherically important photolysis reactions. Among the largest classes of chemicals emitted or produced in the atmosphere are "carbonyls" - organic molecules containing one or more carbonyl functionality. Carbonyls are used in in a vast array of industrial applications, including directly as solvents, pesticides and biofuels, and as reagents for production of pharmaceuticals and aromachemicals. Carbonyls are also ubiquitous in both indoor and outdoor air. Direct emissions are supplemented by in-situ production as virtually all organic compounds break-down through atmospheric oxidation processes via multiple generations of carbonyl intermediates (Figure 1), where they can significantly impact on air quality and health. As an example, carbonyl photolysis has been shown to drive large wintertime ozone formation in the oil and gas "fracking" fields of the Unitah Basin in northeastern Utah.The photochemistry of carbonyls is therefore both chemically interesting and important. Unusually amongst atmospheric organics, they are broken down by abundant UV-A radiation (e.g. Figure 2). Therefore this project is particularly timely, as the photochemical environment is rapidly changing indoors. LED lighting is replacing fluorescent and incandescent technology, whilst UV and plasma based air filtration systems are increasingly used in an effort to enhance indoor air quality and to suppress virus spread.Objectives:To determine absorption cross-sections and photolysis quantum yields for a variety of important gas-phase carbonyl species; to assess photolysis rates and product branching ratios, over a range of indoor and outdoor conditions, and hence air quality impacts; to identify how chemical structure and additional functionalities in carbonyls impact upon photolysis rates. Experimental Approach:(1) Characterisation and development of a newly commissioned fast-flow reactor, coupled to the use of chemosensor radical traps and on-line mass spectrometry for quantum yield determinations (2) UV-vis spectroscopy techniques for absorption cross-section measurements(3) GAUSSIAN quantum chemical toolkit for theoretical thermodynamic calculations and chemical structure determination(4) Development of models incorporating the master chemical mechanism (MCM, mcm.york.ac.uk) for experimental design and environmental impact assessment

光化学控制着一系列自然和人造化学过程：光合作用，等离子体技术，太阳能，燃烧和大气化学。一个重要的例子是大气光氧化，它驱动了大气中的自由基繁殖循环，使主要污染物的排放量损坏，但也控制了次级污染物的形成，例如臭氧和氧化的挥发性有机化合物（VOC），这可以对气候，质量和人类健康产生重大影响。小气相分子与化学活性的超紫色（UV）光相互作用。在此项目中，您将利用新的和新兴的技术，例如低成本的紫外线LED，化学传感器（在约克开发），用于敏感和选择性的自由基检测，在线质谱和现代理论计算方法，以研究气氛重要的光解反应。在大气中发出或生产的最大的化学物质类别是“羰基” - 包含一个或多个羰基功能的有机分子。羰基在各种各样的工业应用中都使用，包括直接作为溶剂，农药和生物燃料，以及用于生产药品和野药剂的试剂。羰基在室内和室外空气中也无处不在。直接排放均由原位产生补充，因为几乎所有有机化合物都通过大气氧化过程通过多代羰基中间体破裂（图1），它们可以对空气质量和健康产生重大影响。例如，已显示羰基光解会在犹他州东北部的Unitah盆地的石油和气体“压裂”田中驱动大型冬季臭氧形成。在大气有机物中，它们异常被大量的UV-A辐射分解（例如，图2）。因此，由于光化学环境正在室内迅速改变，因此该项目尤其及时。 LED照明正在替代荧光和白炽技术，而紫外线和基于等离子体的空气过滤系统越来越多地用于提高室内空气质量并抑制病毒散布。目标：确定吸收跨剖面和光解量子量子，以用于多种重要的气相碳纤维股carbase-Carbonyl;评估光解率和产品分支比率，在室内和室外条件的范围内，从而产生空气质量的影响；确定羰基的化学结构和其他功能对光解率的影响。实验方法：（1）表征和开发新近委托的快速反应器，并使用化学体传感器自由基陷阱和在线质量观察量子测定（2）UV-VIS光检查技术（2）uv-vis spectRoscoppy技术用于吸收横截面测量值（3）高斯定量工具（3）化学工具（3）化学工具（3）实验设计和环境影响评估的化学机制（MCM，MCM.York.ac.uk）