Gas phase spectroscopy ofvan der Waals and hydrogen-bonded cluster ions via photodetachment and photodissociation.

摘要

This dissertation presents the results of a series of experiments aimed at understanding hydrogen bonding and other weak interactions. Although hydrogen bonding is one of the most important and extensively studied interactions in chemistry, the gas phase vibrational spectroscopy of ‘strong’ hydrogen bonds, characterized by high dissociation energies and zero barrier to hydrogen transfer, has proven experimentally challenging, necessitating employment of novel methods of infrared spectroscopy. My colleagues and I have exploited the Free Electron Laser for Infrared experiments (FELIX), a new and high-capability infrared light source, to explore the vibrational spectroscopy of several hydrogen-bonded ions. The combination of FELIX radiation with established techniques for vibrational spectroscopy, including vibrational predissociation and infrared multiphoton dissociation allows for exploration of the broadband vibrational spectroscopy of strong hydrogen bonds. Results are presented that (1) explore the vibrational spectroscopy of the strong hydrogen bond in the model BrHBr− system, (2) seek to understand the effects of solvation on the hydrogen bond through sequential clustering of BrHBr− with HBr molecules, and (3) probe the aqueous hydrogen transfer potential energy surface through vibrational spectroscopy of the H₅O₂ + and D₅O₂+ complex ions. In addition, rare gas halide clusters of Xe_nI − have been probed by anion photoelectron spectroscopy, and resulting spectra have been employed to refine Xe-I pair interaction potentials. These experiments provide information about non-additive and many body effects within the ionic and neutral clusters.