Thesis (Ph. D. in Environmental Science)--Vanderbilt University, Aug. 2007. / Title from title screen. Includes bibliographical references.

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Experimental measurements ol N₂ resonant charge transfer cross sections were performed. It was found that the energy of electrons used to produce the N₂⁺ ions is an important variable with respect to cross section. An examination of the experimental precision was performed and it was found that the precision of measurement was insufficient to determine the exact form of this relationship. The effect of ion energy (collisional energy) was too small to be seen. Modulated detection was used to improve precision and permit measurement at high noise levels. A description of the apparatus is provided. Consideration of other systems and the suitability of their resonant charge transfer reactions for experimental investigation is discussed. Various theoretical models for estimation of cross section were examined. / M.S.

Total charge-transfer cross sections have been obtained in the N₂⁺ - N₂ system with relative ion energies at seven different values between 9 and 441 eV. Data is obtained to examine the curvature and structural relation between total cross section versus ion energy. The effect of ion beam excitation on the cross sections was studied by varying the electron ionization energy in the mass spectrometer ion source over electron energies at eight different values, between 11.6 and 32.1 eV. The dependence of total cross section on the neutralization chamber gas pressure was examined by obtaining data at four different pressure values from 9.9 to 19.9 x 10⁻⁵ torr. Subsequent data treatment provided 56 different cross section values that are with and theoretical results of other investigators. / Ph. D.

No / The reversible in situ formation of a self-assembly building block (naphthalenediimide (NDI)–dipeptide conjugate) by enzymatic condensation of NDI-functionalized tyrosine (NDI-Y) and phenylalanine-amide (F-NH2) to form NDI-YF-NH2 is described. This coupled biocatalytic condensation/assembly approach is thermodynamically driven and gives rise to nanostructures with optimized supramolecular interactions as evidenced by substantial aggregation induced emission upon assembly. Furthermore, in the presence of di-hydroxy/alkoxy naphthalene donors, efficient charge-transfer complexes are produced. The dynamic formation of NDI-YF-NH2 and electronic and H-bonding interactions are analyzed and characterized by different methods. Microscopy (TEM and AFM) and rheology are used to characterize the formed nanostructures. Dynamic nanostructures, whose formation and function are driven by free-energy minimization, are inherently self-healing and provide opportunities for the development of aqueous adaptive nanotechnology.

DNA sequences containing contiguous AA or TT mismatches, as well as sequences containing a 3-deazacytidine analogue were synthesized. Irradiation of anthraquinone abstracts an electron from the DNA. The loss of an electron from double-stranded DNA results in the formation of a radical cation that migrates through the DNA where it reacts irreversibly with H2O or O2 at GG steps. Subsequent treatment with piperidine or Fpg enzyme cleaves the backbone of the DNA at the site of reaction. DNA oligomers were designed to contain contiguous AA, TT, or G3-deazacytidine mismatches. It was revealed that the mismatches destabilize the duplex DNA; however, there is no measurable effect on the overall secondary structure of the DNA. The contiguous (AA)n mismatch, where n lt 7, was shown to have no effect on charge migration efficiency. In contrast, the contiguous (TT)n mismatch, where n gt 2, was shown to have near complete inhibition of charge migration through the mismatch region. Charge migration through the G3-deazacytidine mismatch was shown to have no effect on charge migration efficiency as well. Interestingly, reaction at the (G3-deazacytidine)2 base pairs revealed a change in the ratio of oxidative damage at the Gs. In (GC)2 base pairs, the ratio of damage at the two Gs is 10:1 with the majority of damage occurring at the 5-G. However, the (G3-deazacytidine)2 base pairs had an equal distribution of damage at the 5 and 3-Gs, with the amount of total reactivity equaling the (GC)2 base pairs. These findings indicate that the base composition in mismatched DNA determines the effect on charge migration efficiency and trapping reactivity.

The technique of X-ray diffraction has been used to investigate compounds which show charge-transfer properties in the solid state. It is shown how the results of structure determination can, under favourable conditions, give information about charge-transfer processes. Two sets of compounds have been studied, both of which contain metal-chloride bonds. The first is a series of mixed-valence cobalt hexammine chlorocuprates in which the average oxidation state of the copper can take any value between 1 and 2. The structure of the single-valence (copper (I)) compound, [Co(NH₃)₆]₄Cu₅Cl₁₇ was solved and data was also collected for a compound with Cu(I)/total Cu ~ 0.25. This was shown to have a structure to the single-valence copper (I) and copper (II) compounds and probable arrangements for the Cu(I) and Cu(II) ions are presented. It is shown that linear Cu-Cl-Cu bridges are almost certainly present and that these can account for the charge-transfer spectrum. A new chlorocuprate anion, [Cu₅Cl</sub>16</sub>]^11- was discovered, which has 23(T) symmetry.