In this dissertation, I present electronic spectroscopy of a few biologically
relevant species and their complexes with solvent molecules in the gas phase using
a variety of techniques, including resonantly enhanced multiphoton ionization
(REMPI), laser induced fluorescence (LIF), and zero kinetic energy (ZEKE)
photoelectron spectroscopy. My work on several methylated uracils and thymines
and thymine-water complexes alludes to a new interpretation with regard to the
origin of the photostability of our genetic code. I believe that it is the water solvent
that stabilizes the photophysical and photochemical behavior of these bases under
UV irradiation. For systems that demonstrate vibrational resolution in the first
electronically excited state (S₁) and the cationic state, I performed vibrational
analysis of both states with the aid of ab initio and density functional calculations.
These observations are explained in terms of the structural changes from the
ground state to S₁ and further to the cation. To bridge results from the gas phase to
the solution phase, I also report studies of supersonically cooled water complexes
of the three isomers of aminobenzoic acid. Density functional theory calculations are carried out to identify structural minima of water complexes in the ground state.
The solvation mechanism is investigated based on vibrational analysis of the S₁
state of the neutral complex and the shift of ionization thresholds with increasing
water content. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29759 |
| Date | 27 January 2005 |
| Creators | He, Yonggang |
| Contributors | Kong, Wei |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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