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

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.