ELECTRONIC MATRIX ISOLATION SPECTROSCOPIC STUDIES OF METAL ATOM PHOTOCHEMISTRY

[摘要] This dissertation presents the results of chemical research efforts directed in three areas: (1) the final design of an ultraviolet-visible absorption and emission matrix isolation apparatus is described, (2) by employing this apparatus, molecular scale interactions of the 1:1 metal-water adduct are investigated utilizing electronic absorption spectroscopy, and (3) molecular orbital and electronic state-to-state correlations are invoked to interpret the chemical reaction dynamics of the adducts along ground and excited potential energy surfaces. The final design of this matrix isolation apparatus incorporated unique features that abbreviated data acquisition time and obviated several experimental problems that have plagued previous matrix isolation studies. The investigations of the molecular interactions and reactions of the Group IIA metal atoms (Mg, Ca, Sr, Ba), the Group IIIA metal atoms (Al, Ga, In), and the Group IVA metal atoms (Si, Ge, Sn, Pb) with water molecules isolated in rare gas matrices at 15 K are reported. In most instances, the strength of the metal-water interaction is sufficiently strong to perturb significantly the electronic structure of the metal atom which results in a unique band structure for the adduct that is red-shifted from the metal atomic resonance transition. Selective photolysis studies contributed to a better understanding of the electronic structure of the adduct. Molecular orbital theory is invoked to interpret the nature of the ground and excited states of the metal-water adduct. By resorting to molecular orbital and electronic state correlation methods, the qualitative features of the metal-water interaction potential energy surfaces are derived which predicate the chemical reaction dynamics that, in turn, result in a fundamental understanding of relative reactivities, photochemical pathways, and chemiluminescent processes. In addition, this dissertation reports studies of the electronic structures of the Group IIIA metal suboxides (Al(,2)O, Ga(,2)O, In(,2)O) in absorption and emission. Progressions in the symmetric stretching and bending modes for the ground and excited states are observed. Finally, previously undocumented electronic structures of several metal dimers (Al(,2), Ba(,2), Ge(,2)) are reported and discussed.

[发布机构] Rice University