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Multifrequency electron paramagnetic resonance of ultramarine blue |
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| Authors: | G. R. Eaton S. S. Eaton J. W. Stoner R. W. Quine G. A. Rinard A. I. Smirnov R. T. Weber J. Krzystek A. K. Hassan L. C. Brunel A. Demortier |
| Affiliation: | 1. Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA 2. Department of Engineering, University of Denver, Denver, Colorado, USA 3. College of Medicine, University of Illinois at Urbana-Champaign, Illinois, USA 5. EPR Division, Broker BioSpin Corporation, Manning Park, Billerica, Massachusetts, USA 6. Center for Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA 8. Laboratoire de Spectrochimie Infrarouge et Raman, Unité Mixte de Recherche 8516 du Centre National de la Recherche Scientifique, Haute Etudes Industrielle Lille, Lille, France |
| Abstract: | Electron paramagnetic resonance spectra of the S3/? radical center in ultramarine blue over a factor of about 2500 in frequency (258 MHz to 670 GHz) reveal a substantially Lorentzian shape, without resolution of g anisotropy. Variable temperature measurements found that the line width is independent of temperature, within experimental uncertainty, up to about 90 K at 9.5 GHz and between ca. 5 K and room temperature at 95 and 217 GHz, as expected for an exchange-narrowed signal. Analysis of the increase in the low-temperature line width as a function of frequency above 9 GHz is consistent with an exchange interaction of about 2· 10?2 K. The line width increases as frequency is decreased from 2.7 GHz to 258 MHz which is attributed to the contribution from nonsecular terms that has been denoted the “10/3” effect. |
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