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ELECTRONIC STRUCTURE AND SPECTROSCOPY OF RADICALS IN THE GAS
AND CONDENSED PHASES
by
Piotr Adam Pieniazek
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)
August 2008
Copyright 2008 Piotr Adam Pieniazek
Object Description
| Title | Electronic structure and spectroscopy of radicals in the gas and condensed phases |
| Author | Pieniazek, Piotr Adam |
| Author email | pap@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemistry |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-06-06 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-07-25 |
| Advisor (committee chair) | Bradforth, Stephen E. |
| Advisor (committee member) |
Krylov, Anna I. Wittig, Curt Dappen, Werner |
| Abstract | Understanding radicals is central to understanding the mechanics of chemical change. In this work, quantitative and qualitative methods for the description of the electronic spectroscopy of open-shell species in the gas and condensed phases are developed.; Dimer radical cations are important model systems for studying ionization and charge transfer processes. Achieving a reliable theoretical description for these systems is difficult due to the symmetry-breaking of the open-shell Hartree-Fock reference and near-degeneracies. The equation-of-motion coupled-cluster for ionization potentials (EOM-IP-CC) method implemented and benchmarked here remedies these problems by using the corresponding closed-shell reference. It is combined with a qualitative Dimer Molecular Orbitals -- Linear Combination of Fragment Molecular Orbitals (DMOLCFMO) framework to elucidate the electronic states of benzene dimer and water dimer cations. In the former case the geometry of the ground state changes from a T-shaped neutral to a displaced sandwich cation. Charge resonance bands, whose spectral location and intensity are sensitive to the geometry of the system, are present in both isomers. A reordering of electronic states in the local excitation region in the sandwich structure is observed. For the water dimer vertical ionization occurs from the hydrogen-bond donor and induces a proton transfer reaction. The evolution of the electronic spectroscopy along the reaction coordinate is studied. The initial spectrum consists of mixed local and charge-transfer excitations, while the spectrum of the final product resembles that of the hydroxyl radical product. An empirical correction to the density functional theory (DFT) approach used in larger condensed phase Car-Parrinello simulations is benchmarked.; A fully condensed phase treatment is applied for the cyano radical in water. Conflicting assignments appeared in the literature as to the position of the absorption band of aqueous CN. Classical molecular dynamics simulations are combined with accurate ab initio calculations to unravel the effect of water on the two lowest electronic states of cyano radical. Accurate dimer calculations are used to parametrize the force field. A minor blue-shift of the intervalence transition energies is observed, contradicting previous experimental assignments. |
| Keyword | quantum chemistry; electronic spectroscopy |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m1417 |
| Contributing entity | University of Southern California |
| Rights | Pieniazek, Piotr Adam |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Pieniazek-20080725 |
| Archival file | uscthesesreloadpub_Volume32/etd-Pieniazek-20080725.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | ELECTRONIC STRUCTURE AND SPECTROSCOPY OF RADICALS IN THE GAS AND CONDENSED PHASES by Piotr Adam Pieniazek A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CHEMISTRY) August 2008 Copyright 2008 Piotr Adam Pieniazek |
