Rapid-Scan Electron Paramagnetic Resonance of Highly Resolved Hyperfine Lines in Organic Radicals

Chemphyschem. 2020 Nov 17;21(22):2564-2570. doi: 10.1002/cphc.202000701. Epub 2020 Oct 20.

Abstract

X-band (ca. 9 GHz) fluid solution rapid-scan electron paramagnetic resonance spectra are reported for radicals with multiline spectra and resolution of hyperfine lines as narrow as 30 mG. Highly-resolved spectra of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy, diphenylnitroxide, galvinoxyl, and perylene cation radical with excellent signal-to-noise are shown, demonstrating the capabilities of the rapid-scan technique to characterize very small, well-resolved hyperfine couplings. To acquire high resolution spectra the signal bandwidth must be less than the resonator bandwidth. Signal bandwidth is inversely proportional to linewidth and proportional to scan rate. Resonator bandwidth is inversely proportional to resonator Q. Proper selection of scan rate and resonator Q is needed to achieve resolution of closely-spaced narrow EPR lines.

Keywords: galvinoxyl radical; nitroxide; perylene cation radical.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzhydryl Compounds / chemistry*
  • Cyclic N-Oxides / chemistry*
  • Electron Spin Resonance Spectroscopy
  • Free Radicals / chemistry
  • Molecular Structure
  • Nitrogen Oxides / chemistry*
  • Perylene / chemistry*

Substances

  • Benzhydryl Compounds
  • Cyclic N-Oxides
  • Free Radicals
  • Nitrogen Oxides
  • 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-1-yloxyl
  • Perylene
  • nitroxyl
  • galvinoxyl