Rapid-scan coherence signals in X-band EPR spectra of semiquinones with small hyperfine splittings.
Rapid-scan EPR signals for semiquinones with very-small well-resolved hyperfine splittings exhibit coherence signals at a time after passing through the EPR line that is proportional to the reciprocal of the hyperfine splitting. Such coherences are a general phenomenon due to constructive interference of the responses to transient excitation of spins by rapid scan of the magnetic field across equally spaced spin packets. Examples are shown for 2,3,5,6-tetramethoxy-1,4-benzosemiquinone with aH=46 mG for 12 protons and for 2,5-di-t-butyl-1,4-benzosemiquinone with aH=59 mG for 18 protons.
Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
Hanan
H
Elajaili
School of Engineering and Computer Science, University of Denver, Denver, CO 80208, USA.
George A
GA
Rinard
Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
Zhelin
Z
Yu
Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
Deborah G
DG
Mitchell
School of Engineering and Computer Science, University of Denver, Denver, CO 80208, USA.
Richard W
RW
Quine
Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
Sandra S
SS
Eaton
Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA. Electronic address: geaton@du.edu.
Gareth R
GR
Eaton
D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry; D011522:Protons; D011809:Quinones / Q000737:chemistry*
D011522:Protons; D011809:Quinones; D010100:Oxygen
FID; Hyperfine splitting; Rapid-scan coherence; Semiquinone