A DNP investigation of pi and final sigma transitions for nitroxide spin probes at 1.53 mT

A weak field DNP study of 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-hydroxy-TEMPO), 4-amino-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-amino-TEMPO), and 2, 2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) free radicals invarious solvents was performed at 1.53 mT using a doubleresonance spectr...

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Bibliographic Details
Published in:Journal of magnetic resonance (1997) 1998-09, Vol.134 (1), p.1-6
Main Authors: Salman, A O, Sünnetçioğlu, M M, Sungur, R, Bingöl, G
Format: Article
Language:English
Subjects:
Bepridil - analogs & derivatives
Bepridil - chemistry
Biphenyl Compounds
Cyclic N-Oxides - chemistry
Electron Spin Resonance Spectroscopy - methods
Free Radicals
Indicators and Reagents
Picrates
Solutions
Spin Labels
Water
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Summary:A weak field DNP study of 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-hydroxy-TEMPO), 4-amino-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-amino-TEMPO), and 2, 2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) free radicals invarious solvents was performed at 1.53 mT using a doubleresonance spectrometer. pi transitions, in which the RF fieldhas a component perpendicular to the static magnetic fieldB0, and final sigma transitions, in which the RF field has a component parallel to B0, were recorded. In order to observe thefinal sigma transitions a new probe head was designed. The final sigma transitions were obtained at the frequencies expected from theoretical calculations. However, the results obtained for the observed enhancements deviated from the values expectedtheoretically.
ISSN:1090-7807