University of Illinois Urbana-Champaign

X-band ENDOR and S-band ESEEM of paramagnetic disordered solids

Crookham, Harry Clark

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Description

Title
X-band ENDOR and S-band ESEEM of paramagnetic disordered solids
Author(s)
Crookham, Harry Clark
Issue Date
1990
Doctoral Committee Chair(s)
Belford, R. Linn
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Physical
Language
eng
Abstract
  • X-band ENDOR and S-band ESEEM have been employed in this study to measure weak electron-nuclear hyperfine and nuclear electric quadrupole couplings in paramagnetic disordered solids. In the X-band ENDOR investigation, radicals generated from perylene adsorbed on catalytically active alumina and silica-alumina surfaces were studied. Complex ENDOR spectra were obtained. The magnitudes of the principal elements of the anisotropic hyperfine matrix for each chemically distinct type of proton could be determined by means of a computer simulation analysis. The hyperfine parameters for radicals on both of the surfaces studied are found to be nearly identical and the radicals are assigned as the perylene cation radical. In addition, matrix ENDOR signals are found to reveal distinct differences between the surface adsorption sites on the two oxides studied. Most notably, a matrix peak attributed to $\sp{27}$Al nuclei is detected from samples prepared with alumina. However, this peak was not detected from samples prepared with the silica-alumina.
  • A description of the world's first S-band ESE spectrometer is presented. The use of lower microwave frequencies (fields) to enhance the modulation depth from weakly coupled nuclei has been investigated with this instrument. Also, an S-band ESEEM investigation of an adduct formed between pyridine and bis(1-phenyl-1,3-butanedianto) copper(II) exemplifies the importance of multi-frequency ESEEM. The investigation also further demonstrates that weak nuclear electric quadrupole coupling information from nuclei such as $\sp{14}$N can be obtained through ESEEM.
Type of Resource
text
Permalink
http://hdl.handle.net/2142/21775
Copyright and License Information
Copyright 1990 Crookham, Harry Clark

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