Experimental and Computational Study of Spectroscopy and Dynamics of Gas-Phase Metal-Ligand Complexes

本项目属于EPSRC催化研究领域，包括用红外光解离光谱研究尺寸选择的气相金属配体络合物的结构和动力学。利用牛津大学独特的装置，金属离子的分子络合物将通过四极质谱进行质量选择，并受到可调谐红外光学参量振荡器的强烈红外辐射。努力将集中在过渡金属离子与大气分子(二氧化碳、N2O、CO、H2O、CH4等)上。并将进行各种实验，包括仪器开发、详细的实验工作和量子化学计算：1)结构测定和低位异构体的作用。“惰性标记信使”技术将与由密度泛函理论确定的低能结构的光谱模拟相结合。这一方法已被证明在确定许多复合体的全球最小结构方面非常成功。2)混配M+/-(L1)n(L2)m络合物的光碎裂动力学和支化率。我们将通过回答一些问题来研究决定裂解过程的重要因素，例如：离开的总是最弱结合的配体吗？是发色团配体吗？在什么情况下，分子内的振动重分布被键断裂/反应阻止？3)簇内反应性。在可能最雄心勃勃的研究中，我们将尝试通过红外光激活特定簇内的配体之间的化学反应。Mackenzie小组以前通过更大的过渡金属簇实现了这一点，但从来没有在金属-配体络合物中观察到过这种情况。这将揭示整个反应势能图景的细节，包括反应势垒、表面跃迁、额外电子激发态的作用等。此外，我将参与柏林的Mackenzie小组和Fielicke小组之间的持续合作，他们可以获得强红外自由电子激光，该激光可以到达牛津实验室可用的波长范围之外的区域。

This project falls within the EPSRC Catalysis research area and consists of the structure and dynamics studies of size-selected gas-phase metal ligand complexes by the infrared photodissociation spectroscopy. Using the unique apparatus in Oxford, molecular complexes of metal ions will be mass-selected via quadrupole mass spectrometry and subjected to an intense IR radiation from a tuneable infrared optical parametric oscillator. Efforts will be concentrated on transition metal ions with atmospheric molecules (CO2, N2O, CO, H2O, CH4 etc.) and a variety of experiments, involving a mixture of instrument development, detailed experimental work and quantum chemical calculations, will be performed: 1) Structure determination and the role of low-lying isomers. The "inert tag messenger" technique will be employed in combination with spectral simulations of low-energy structures determined by density functional theory. This approach has been proven to be highly successful in determining the global minimum structures of many complexes. 2) Photofragmentation dynamics and branching ratios in mixed-ligand M+/-(L1)n(L2)m complexes. We will investigate the factors important in determining the fragmentation process by addressing questions, such as: is it always the most weakly-bound ligand which leaves? Is it the chromophore ligand? Under which circumstances, is the intramolecular vibrational redistribution arrested by bond-breaking/reaction? 3) Intracluster reactivity. In perhaps the most ambitious studies, we will attempt to initiate chemical reactivity between ligands within a particular cluster by activation with infrared light. The Mackenzie group has achieved this previously with larger transition metal clusters but it has never been observed in a metal-ligand complex. This will shed light on details of the full reactive potential energy landscape including reaction barriers, surface hoppings, the role of additional electronically excited states etc. Furthermore, I will be involved with an ongoing collaboration between the Mackenzie group and the Fielicke group in Berlin who have access to an intense infrared free electron laser which can reach wavelength regions beyond those available in the Oxford lab.