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|Title:||Part One: The Quantitative Prediction and Analysis of Enthalpies for The Interaction of Gas Phase Ion-Ion, Gas Phase Ion-Molecule, and Molecule-Molecule Lewis Acid-Base Systems. Part Two: The Study of Intervalence Transfer in Mixed Valence Systems Using Time Domain Reflectometry|
|Author(s):||Kroeger, Michael Kevin|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||In Part One, the equation -(DELTA)H = e(,A)e(,B) + c(,A)c(,B) + t(,A)t(,B) where the subscripts A and B refer to acid and base correlates the enthalpy of Lewis acid-base adduct formation for molecule-molecule, gas phase ion-molecule, and gas phase ion-ion interactions. The parameters obtained are interpreted in terms of electrostatic, covalent, and electron transfer nature of interactions and trends in the parameters are found to agree with qualitative chemical intuition regarding acid-base properties and a semiempirical justification for the electron transfer term is presented. New insights regarding the comparison of gas phase and solution data are provided. The quantitative correlation can be used to indicate instances where variations may occur in the geometry of acid-base adducts. The existence of bonding contributions other than sigma-bond formation is also suggested by this correlation.
In Part Two, time domain reflectometry is used to obtain rates of electron transfer in mixed valence species. Time domain reflectometry measures the dielectric constant of a sample as a function of time by exposing the sample to a voltage pulse and analyzing the reflections. The process of electron transfer between two metal sites in a mixed valence species leads to a change in the orientation of the dipole moment which gives rise to dielectric relaxation. The technique is used to obtain rates of electron transfer for Eu(,3)S(,4) and perovskites of the general formula La(,1-x)Sr(,x)MO(,3), M = Ni, Co, Fe, Mn, 0 < x < 0.3. The results are described in terms of an electron hopping model and the rates obtained for Eu(,3)S(,4) are found to be superior to rates obtained by Mossbauer spectroscopy.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-15|