Electron dipole-dipole ESEEM in field-step ELDOR of nitroxide biradicals

L. V. Kulik, Yu A. Grishin, S. A. Dzuba, I. A. Grigoryev, S. V. Klyatskaya, S. F. Vasilevsky, Yu D. Tsvetkov

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

The use of a rapid stepping of the magnetic field for investigation of electron dipole-dipole ESEEM in pulsed X-band ELDOR is described. The magnetic field jump, synchronized with a microwave pumping pulse, is positioned between the second and the third pulses of the stimulated echo pulse sequence. This echo is measured as a function of the delay between the first and the second pulses. The data are analyzed for a Fourier transform resulting in a Pake resonance pattern. To remove the electron-nuclear contributions to ESEEM, time traces with pumping were divided by those without. This resulted in complete elimination of electron-nuclear contributions, which is seen from the absence of peaks at nuclear frequencies and the similarity of results for protonated and deuterated solvents. For increasing the electron-electron modulation depth, a scanning of the magnetic field during the microwave pumping is proposed. The interspin distances and their distribution are determined for two long-chained (ca. 2 nm) nitroxide biradicals in glassy toluene and in frozen nematic liquid crystal 4-cyano-4′-pentyl-biphenyl. For the latter solvent, the alignment of the axis connecting two nitroxides in biradicals is quantitatively analyzed.

Original languageEnglish
Pages (from-to)61-68
Number of pages8
JournalJournal of Magnetic Resonance
Volume157
Issue number1
DOIs
Publication statusPublished - 1 Jan 2002
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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