PEPICO in combustion chemistry research II

对最重要反应的详细了解对于发展对燃烧过程的预测性理解起着关键作用，对点火过程和减少污染物尤为重要。该项目的目标是详细研究燃料破坏的初始步骤。一个关键的反应是通过从燃料的碳框架中提取氢来形成燃料自由基，因为它导致异构体自由基，在随后的反应中引起反应网络的分支。要正确地描述整个反应网络，必须理解第一个分支步骤。在低温下，燃料自由基通常通过向过氧化物和随后的氧化中间体添加氧来发生反应。在高温下，裂解和单分子分解形成碳氢化合物中间体。采用分子束质谱（MBMS）和光电子-光子-符合谱（PEPICO）相结合的方法，在层流低压火焰和塞流反应器中对反应关键物质进行了检测实验。在瑞士光源的光电离实验补充了基于实验室的电子电离MBMS实验。两位申请人的团队都表明，他们在瑞士光源进行的火焰实验具有卓越的灵敏度，可以比同类MBMS仪器更好地识别和量化异构体。因此，该实验非常适合于检测火焰气体复杂基质中的大多数自由基。为确保高质量的数据评估，要求为Hemberger博士提供墨卡托研究金。由于在流动反应器中可以比在模型火焰中更容易和更系统地控制特定温度下的压力和反应时间，因此将塞流反应器与MBMS PEPICO系统建立并连接是本项目的目标之一。这些实验的目的是通过温度依赖浓度分布来表征通过低温反应途径在更宽参数范围内形成的中间体。两个实验的结合产生了一系列碳氢化合物（丙烯、丙烷、1-丁烯、2-丁烯、1-丁烯、正丁烷、正丁烷、正庚烷、甲基己烷、丙苯和丙基环己烷）的实验数据集，可用于开发和验证低温和高温燃烧的反应机制。本项目工作的重点是识别导致反应网络初始步骤分支的中间体。本项目获得的实验结果将提供给科学界，并与模型开发人员合作进行解释。

A detailed knowledge of the most important reactions plays a key role for the development of a predictive understanding of combustion processes and it is particularly important for ignition processes and the mitigation of pollutants. The goal of this project is to investigate the initial steps of fuel destruction in detail. A key reaction is the formation of a fuel radical by hydrogen abstraction from the carbon frame of the fuel because it leads to isomeric radicals, which in subsequent reactions cause branching in the reaction network. To describe the complete reaction network correctly, the first branching steps must be understood. At low temperatures, the fuel radicals typically react by oxygen addition to peroxides and subsequently oxygenated intermediates. At high temperatures, beta-scissions and unimolecular decomposition form hydrocarbon intermediates. A combination of molecular-beam mass spectrometry (MBMS) and photoelectron-photoion-coincidence spectroscopy (PEPICO) is used to detect the reactive key species experimentally in laminar low pressure flames and in a plug-flow reactor. The experiments with photoionization at the Swiss Light Source are complemented with laboratory based MBMS experiments using electron ionization. The teams of both applicants showed that their flame experiment at the Swiss Light Source features exceptional sensitivity and can identify and quantify isomers better than comparable MBMS instruments. As a consequence, this experiment is ideally suited to detect the mostly radical species in the complex matrix of the flame gases. A Mercator-fellowship for Dr. Hemberger is requested to ensure a high quality of data evaluation. Because the pressure and the reaction times at a specified temperature can be controlled easier and more systematically in a flow reactor than in a model flame, it is one target of this project to build and connect a plug-flow reactor to the MBMS PEPICO system. The goal of these experiments is to characterize the intermediates formed via low-temperature reaction pathways in a wider parameter range by temperature-dependent concentration profiles.A combination of both experiments yields experimental data sets for a series of hydrocarbons (Propene, Propane, 1-Butene, 2-Butene, i-Butene, n-Butane, i-Butane, n-Heptane, Methylhexane, Propylbenzene und Propylcyclohexane) that can be used to develop and validate reaction mechanisms for low and high temperature combustion. The focus of the work in this project is the identification of intermediates that lead to branching in the initial steps of the reaction network. The experimental results obtained in this project will be provided to the scientific community and interpreted in cooperation with model developers.