Scattering of State-Selected and Oriented Hydroxyl Radicals by Halogen Hydrides and Xenon
Scattering of State-Selected and Oriented Hydroxyl Radicals by Halogen Hydrides and Xenon
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卤化物和氙对状态选择和定向羟基自由基的散射
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
A. Moise
中科院分区：
文献类型：
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作者：
A. Moise
OH自由基与原子和其他分子的相互作用与大气、燃烧和星际化学中涉及的许多物理和化学过程有关。各种实验和理论研究已经揭示了关于羟基自由基与稀有气体原子如He、Ar、Ne和分子如H2、N2、CH 4、CO和CO2的相互作用的信息。OH-Ar非弹性散射的理论和实验结果之间的一个非常好的协议，从而证实了理论模型的准确性。本文介绍了正交分子束实验，研究了HCl、HBr、HI和H2O对OH分子的散射。状态-状态截面和空间不对称性的测量，探测这些原子硅藻或硅藻-硅藻系统的完整的势能面（PES）。所采用的实验技术是：超声分子束扩展，放电，静电场聚焦和选择的OH分子在一个单一的内部能量状态，并将它们与H-侧或O-侧朝向碰撞伙伴，激光诱导荧光，共振增强多光子电离和速度图成像。得到的旋转非弹性截面表明OH-HCl，OH-HBr和OH-HI散射系统之间的相似性。一般情况下，自旋轨道守恒过渡占主导地位，的双重过渡具有最大的横截面和横截面的大小随旋转激发。测得的空间不对称性反映了较高的各向异性的OH-HCl相互作用势。测量了OH-HBr和OH-HI的小空间不对称性。实验空间不对称性的大小和符号与PES极小值的分子构型和反应的发生之间的可能的相关性被认为是。为了丰富对OH-稀有气体相互作用的认识，本文给出了OH分子被氘散射的态-态非弹性截面和空间不对称性。将实验结果与理论结果以及先前报道的OH-He和OH-Ar散射的结果进行了比较。观察到的主要差异进行了讨论，旨在理解的贡献的相互作用的特定类型的分子间力。
The interaction of the OH radical with atoms and other molecules is relevant for many physical and chemical processes involved in atmospheric, combustion and interstellar chemistry. Various experimental and theoretical studies have revealed information concerning the interaction of the hydroxyl radical with rare gas atoms like He, Ar, Ne and molecules like H2, N2, CH4, CO and CO2. A remarkably good agreement between the theoretical and experimental results was obtained for the OH-Ar inelastic scattering, confirming thus the accuracy of the theoretical models. In this thesis crossed molecular beams experiments are presented in which the scattering of OH molecules by HCl, HBr, HI and Xe is studied. State-to-state cross-sections and steric asymmetries are measured which probe the complete Potential Energy Surfaces (PES) for these atom-diatom or diatom-diatom systems. The experimental techniques employed are: supersonic molecular beam expansions, electrical discharge, electrostatic fields to focus and select the OH molecules in a single internal energy state and to orient them with the H-side or the O-side towards the collision partner, laser induced fluorescence, resonance enhanced multiphoton ionization and velocity map imaging. The rotational inelastic cross sections obtained indicate similarities among the OH-HCl, OH-HBr and OH-HI scattering systems. Generally, the spin-orbit conserving transitions dominate, the -doublet transition exhibits the largest cross-section and the magnitude of the cross-sections decreases with rotational excitation. The measured steric asymmetries reflect the higher anisotropy of the OH-HCl interaction potential. Small steric asymmetries are measured for OH-HBr and OH-HI. A possible correlation between the magnitude and sign of the experimental steric asymmetries with the molecular configurations for the PES minima and the occurrence of the reactions is considered. In order to enrich the knowledge of the OH-rare gases interaction, state-to-state inelastic cross sections and steric asymmetries for the OH molecule scattered by Xe are presented. The experimental results are compared with the theoretical results and with the previously reported results for OH-He and OH-Ar scattering. The major differences observed are discussed aiming at the understanding of the contribution to the interaction of specific type of the intermolecular forces.