ANION PHOTOELECTRON SPECTROSCOPIC STUDIES: FROM BIOMOLECULES, TO SIMPLE ORGANICS, TO METAL COMPOUNDS

negative ions;photoelectron spectroscopy;gas phase;anions;Chemistry

Buonaugurio, Angela Marie

Johns Hopkins University

关键词: negative ions;    photoelectron spectroscopy;    gas phase;    anions;    Chemistry;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/39291/AMB_thesis_1.docx?sequence=2&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Photoelectron spectroscopic studies on gas phase mass-selected anions were performed on a variety of molecular systems. These studies are grouped by themes culminating into five chapters discussing biomolecules, electron induced proton transfer, alkoxides, metal oxides, metal cluster reactivity, and electron binding to aromatic molecules. These experiments were primarily performed in the Bowen lab at Johns Hopkins University using our continuous negative ion photoelectron spectrometer. The metal oxide studies were performed on our pulsed negative ion photoelectron spectrometer while the metal cluster reactivity studies were carried out on location at Karlsruhe institute of Technology (KIT), Germany under Professor Hansgeorg Schnӧckel using an FT-ICR mass spectrometer.The study of nucleic acid bases (nucleobases) and their interaction with low energy electrons elucidates a better molecular-level understanding of radiation induced mutagenesis (Chapter 1). Additionally, studies of hydrated and rare-gas solvated nucleobase anions provide strong evidence supporting the co-existence of dipole-bound and valence anion states. Modified uracil analogues 6-azauracil and 5-substituted derivatives are discussed in relation to their properties as radiosensitizers. Electron-induced proton transfer studies (Chapter 2) yields information on the most fundamental processes in chemistry. Intramolecular hydrogen bonding is important to the aforementioned biomolecule systems, but carrying out experiments on the systems acetoacetic acid and oxalic acid allow for better insight utilizing molecules with a larger vapor pressure. The system of 1,8-bis(dimethylamino)naphthalene, HCl and an excess electron inducing intermolecular proton transfer presents a novel acid-base interaction that demonstrates the fundamental processes of how salt complexes are formed.Chapter 3 presents the adiabatic electron affinities and vertical detachment energies of a series of deprotonated alcohols, also referred to as alkoxides. This information yields O-H bond dissociation energies of the corresponding alcohol using the gas phase acidities of the associated alcohol of interest and the thermochemical cycle. Zirconium and hafnium transition metal oxides presented in Chapter 4 examines metals with similar physical properties do not necessarily form oxides that will also exhibit similar properties. Reactivity studies were performed with Al/Ga13¯ and surrounding cluster sizes reacting with O2. This is to further study the odd/even reactivity effect and improve characterization of these clusters, Al/Ga13¯ specifically, for use in cluster-assembled materials. Finally, binding of an excess electron to several aromatic systems are discussed in Chapter 5. Benzaldehyde exhibits a unique spectral profile as a result of vibrational progressions from electron attachment. p-Nitroaniline and the chiral molecules of N-paranitrophenylsulfonylalanine and N-paranitrophenylalanine were studied to determine how the smaller molecular components may affect the physical properties of the larger molecular complex.