Investigation of the reaction kinetics of precursor systems in shock-tube and flow-reactor experiments supported with quantum-chemical/statistical calculations

许多技术上重要的颗粒合成过程都是通过气相反应进行的，在气相反应中，气体前体反应形成浓缩的反应产物。为了理解、模拟和优化整个过程，需要了解基本的动力学知识。本提案有主题、有系统地开展TP1项目正在进行的工作。目的是研究激波反应器和流动反应器中铁前驱体的气相反应和非均相反应。实验数据的分析得到了理论工作的支持。这一阶段的中心主题是：(1)激波管和流动反应堆中前驱体动力学的研究：这项工作的主要重点是确定选定的Fe和Si前驱体的动力学。对于物种检测，使用飞行时间质谱仪、气相色谱和激光光谱分析。对于在较低温度和较长测试时间下的前体反应，使用流动反应器。作为流动反应器中的另一种检测方法，激光诱导荧光与TP7(Dreier|Schulz)配合使用来定量中间物种(SiO、Fe、FeO)。(2)在流动反应器和激波管中提供颗粒的多相反应的研究：多相反应在单组分(气体-颗粒相互作用)和混合体系(例如，制备核-壳结构)中都是有意义的。在这种情况下，研究有颗粒存在的前体分解是很有意义的，应该主要在流动反应器中进行。(3)含硅前驱体与H、OH自由基反应的研究：这些反应在火焰中合成颗粒过程中起着重要作用。对于时间分辨检测，利用原子共振吸收光谱和环形染料激光吸收光谱来监测与H和OH物种的反应。(4)SiO和FeO在激波管中吸收截面的测定：SiO和FeO是合成二氧化硅和氧化铁纳米颗粒和氧化铁薄膜的重要中间产物。用激光诱导荧光法测定了TP7在第一个投影期的相对SiO浓度分布。然而，定量所需的光谱数据在文献中没有充分的记录。因此，有必要测定这些中间体在激波管中的吸收截面。(5)量子化学和统计计算：对于第一项和第三项，上述反应和分子的量子化学表征提供了相关分解通道的热化学和动力学数据，支持反应机理和构效关系的发展。

Many technologically important particle synthesis processes proceed via gas-phase reactions where gaseous precursors react to form condensed reaction products. The knowledge of the underlying kinetics is required in order to understand, simulate, and optimize the overall process. The present proposal pursues thematically and methodically the ongoing work of the TP1 project. The aim is to investigate the gas-phase reactions as well as heterogeneous reactions of iron precursors in shock-wave reactors and in a flow reactor. The analysis of the experimental data is supported by theoretical work. The central topics of this phase are: (1) Investigation of precursors kinetics in the shock tube and in the flow reactor: The main focus of this work is the determination of the kinetics of selected Fe and Si precursors. For species detection, time-of-flight mass spectrometry, gas chromatography and laser spectroscopy are used. For precursor reactions at lower temperatures and longer test times, a flow reactor is used. As an additional detection method in the flow reactor, laser-induced fluorescence is used in cooperation with TP7 (Dreier|Schulz) to quantify intermediate species (SiO, Fe, FeO). (2) Investigation of heterogeneous reactions by supplying particles in the flow reactor and in the shock tube: heterogeneous reactions are of interest both in one-component (gas-particle interaction) and in mixed systems (for example, for the preparation of core-shell structures). In this context, the study of precursor decomposition in the presence of particles is of interest and should be carried out primarily in the flow reactor. (3) Investigation of the reactions of Si-containing precursors with H and OH radicals: These reactions play an important role during the particle synthesis in flames. For time-resolved detection, reactions with H and OH species are monitored with atomic resonance absorption spectroscopy and ring-dye laser absorption spectroscopy.(4) Determination of absorption cross-sections of SiO and FeO in the shock tube: SiO and FeO are important intermediates during the synthesis of silicon and iron oxide nanoparticles and layers. Relative SiO concentration distributions were determined in TP7 in the first project period by laser-induced fluorescence. However, the spectroscopic data required for the quantification are insufficiently documented in the literature. Therefore, it is necessary to determine absorption cross-sections of these intermediates in the shock tube. (5) Quantum-chemical and statistical calculations: For items 1 and 3, the quantum-chemical characterization of the above reactions and molecules provides thermochemical and kinetic data of relevant decomposition channels which support the development of reaction mechanisms and Structure-Activity Relationships.