High Resolution Spectroscopy of Transition Metal-Containing Free Radicals: Investigating High Angular Momentum States

Persistent Link:
http://hdl.handle.net/10150/195805
Title:
High Resolution Spectroscopy of Transition Metal-Containing Free Radicals: Investigating High Angular Momentum States
Author:
Flory, Michael Aaron
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Small diatomic and triatomic 3d transition metal species are excellent model systems for understanding metal-ligand interactions important to larger complexes. Because of the unpaired 3d electrons, these radicals often occur in states with high angular momentum (electron spin, orbital, or nuclear spin). Three questions are particularly relevant to studying monosubstituted 3d metal compounds. What are the fundamental geometric, bonding, and electronic properties? How accurately does currentquantum mechanical theory describe the interactions in high spin states? Assuming these molecules may be present in the interstellar medium, what are the precise transition frequencies that can be used for radioastronomy?To answer these questions, pure rotational spectroscopy has been applied to eleven simple molecules containing 3d transition metals. The small radicals were synthesized in the gas phase and examined in situ. Both direct absorption, submillimeter spectroscopy and Fourier transform microwave spectroscopy were used to cover thefrequency range 8-660 GHz. New synthetic techniques, including oven-insulating methods, use of a longitudinal AC discharge, and emphasis on organometallic precursors, were developed to improve reaction yields.Spectra were recorded for four categories of 3d metal compounds: vanadium molecules, cobalt radicals, zinc species, and several monocyanides. Frequently, the data exhibited signs of perturbations either from low-lying excited electronic states, a common feature with 3d electrons, or from avoided crossings of hyperfine levels. The data were analyzed using effective Hamiltonians, and spectroscopic constants have been determined for rotational, fine structure, and hyperfine interactions. The measurements haveprovided transition frequencies as references for astronomical studies; these values are accurate to within 50 kHz for direct measurements and usually within 100 kHz for frequencies calculated from determined molecular constants.Rotational constants have been used to establish precise molecular geometries. Fine structure and hyperfine data provided insight into 3d metal bonding properties (molecular orbital composition and electron distribution) and structure of electronic state manifolds. In some cases, it was necessary to develop new terms for the Hamiltonian expressions to accurately describe the interactions observed in the spectra. These terms include deperturbation parameters and the first complete description of lambda-doubling for Phi states.
Type:
text; Electronic Dissertation
Keywords:
spectroscopy; bonding; quantum mechanics; radicals; metals
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Ziurys, Lucy M
Committee Chair:
Ziurys, Lucy M

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleHigh Resolution Spectroscopy of Transition Metal-Containing Free Radicals: Investigating High Angular Momentum Statesen_US
dc.creatorFlory, Michael Aaronen_US
dc.contributor.authorFlory, Michael Aaronen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractSmall diatomic and triatomic 3d transition metal species are excellent model systems for understanding metal-ligand interactions important to larger complexes. Because of the unpaired 3d electrons, these radicals often occur in states with high angular momentum (electron spin, orbital, or nuclear spin). Three questions are particularly relevant to studying monosubstituted 3d metal compounds. What are the fundamental geometric, bonding, and electronic properties? How accurately does currentquantum mechanical theory describe the interactions in high spin states? Assuming these molecules may be present in the interstellar medium, what are the precise transition frequencies that can be used for radioastronomy?To answer these questions, pure rotational spectroscopy has been applied to eleven simple molecules containing 3d transition metals. The small radicals were synthesized in the gas phase and examined in situ. Both direct absorption, submillimeter spectroscopy and Fourier transform microwave spectroscopy were used to cover thefrequency range 8-660 GHz. New synthetic techniques, including oven-insulating methods, use of a longitudinal AC discharge, and emphasis on organometallic precursors, were developed to improve reaction yields.Spectra were recorded for four categories of 3d metal compounds: vanadium molecules, cobalt radicals, zinc species, and several monocyanides. Frequently, the data exhibited signs of perturbations either from low-lying excited electronic states, a common feature with 3d electrons, or from avoided crossings of hyperfine levels. The data were analyzed using effective Hamiltonians, and spectroscopic constants have been determined for rotational, fine structure, and hyperfine interactions. The measurements haveprovided transition frequencies as references for astronomical studies; these values are accurate to within 50 kHz for direct measurements and usually within 100 kHz for frequencies calculated from determined molecular constants.Rotational constants have been used to establish precise molecular geometries. Fine structure and hyperfine data provided insight into 3d metal bonding properties (molecular orbital composition and electron distribution) and structure of electronic state manifolds. In some cases, it was necessary to develop new terms for the Hamiltonian expressions to accurately describe the interactions observed in the spectra. These terms include deperturbation parameters and the first complete description of lambda-doubling for Phi states.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectspectroscopyen_US
dc.subjectbondingen_US
dc.subjectquantum mechanicsen_US
dc.subjectradicalsen_US
dc.subjectmetalsen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorZiurys, Lucy Men_US
dc.contributor.chairZiurys, Lucy Men_US
dc.contributor.committeememberLichtenberger, Dennis L.en_US
dc.contributor.committeememberSanov, Andreien_US
dc.contributor.committeememberSmith, Mark A.en_US
dc.contributor.committeememberWalker, F. Annen_US
dc.identifier.proquest2301en_US
dc.identifier.oclc659748152en_US
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