KSEF RDE: Photoelectron Velocity-Map Imaging of Transition Metal-Aromatic Clusters

This proposal outlines a research project concerning the electronic states and molecular structures of group 3 (Sc, Y, and La) transition metal-aromatic clusters. These organometallic clusters will be synthesized in a laser vaporization molecular beam source and mass identified by photoionization time-of-flight mass spectrometry. Vibrationally resolved electronic spectra will be measured with photoelectron velocity-map-imaging. Key experimental results are precise ionization energies, metal-ligand and ligand-based vibrational frequencies, and electric charge effects on molecular structures. The ionization energy is a basic thermochemical property of a molecule and is used to obtain the metal-ligand bond energy of the neutral cluster through a thermodynamic relation. The metal-ligand vibrational frequencies give direct evidence about the metal-ligand bonding, whereas the ligand-based vibrational frequencies probe the geometry of metal-coordinated aromatic molecules. Structural isomers and electronic states of the metal-aromatic clusters are identified by comparing the photoelectron imaging data and theoretical predictions. The success of this work will expand our research program in a new direction and advance the fundamental understanding about how metal centers interact with and activate aromatic molecules. It will open up new applications of the photoelectron velocity-map imaging method and enhance Kentucky's emerging international reputation in this field. Moreover, this work will provide training of students in laser spectroscopy, mass spectrometry, and computational chemistry and in the design, operation, and interpretation of scientific experiments.