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|Title:||Computer-assisted analysis of electron magnetic resonance spectra and the electron nuclear double resonance spectrum of isolated perylene cations|
|Author(s):||Mattson, Karen Jean|
|Doctoral Committee Chair(s):||Belford, R. Linn|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The analysis of electron paramagnetic resonance (EPR) spectra and the spectra from related techniques such as electron nuclear double resonance (ENDOR) spectroscopy, requires simulation of the experimental spectra. Simulating an experimental spectrum involves varying the values of several spectral parameters until the resultant simulation best reproduces the experimental spectrum. Trial-and-error fitting of the parameters is often time-consuming and difficult, limiting the number of spectra which can be simulated. A procedure has been developed to automate the process of fitting the spectral parameters. It is based on the Simplex method of optimization and uses a least-squares response function to mathematically compare trial simulations with the experimental spectrum. Details of the program are discussed. Examples of its use in fitting the hyperfine coupling constants of ENDOR spectra are given.
As part of an effort to apply electron magnetic resonance techniques to the study of coal, the ENDOR spectrum of isolated perylene cations was obtained. Perylene and other polycyclic aromatic hydrocarbons are studied as models of the compounds contained in coal. These compounds are easily oxidized by activated silica-alumina. The spectrum of isolated cations was obtained to determine if the hyperfine values measured from the adsorbed cations are altered by their interaction with the surface.
The isolated cations were created by oxidation in concentrated sulfuric acid. The similarity of the spectra demonstrates that the hyperfine values of the adsorbed cations are not altered by their interaction with the surface. This implies that the cation-surface interaction is not strong and that it is symmetric. These spectra also provide the first direct evidence for the sole formation of cation radicals on activated silica-alumina.
|Rights Information:||Copyright 1990 Mattson, Karen Jean|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9114337|