Magnetic field effects and time-resolved EPR studies on the photogenerated biradicals in phenothiazine-C60 linked systems: Clarification of the mechanism of novel magnetic field effects by dependences of methylene chain length and temperature

Shinya Moribe, Hiroaki Yonemura, Sunao Yamada

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9 Citations (Scopus)

Abstract

Magnetic field effects (MFEs) on photogenerated biradical in phenothiazine (Ph)-C60 linked compound with four methylene group (Ph(4)C60) have been investigated. Transient absorption spectra showed photoinduced intramolecular electron-transfer reactions from the Ph to triplet excited state of C60(3 C60*) . With increasing magnetic field, the decay rate constant of the photogenerated biradical decreased steeply at lower magnetic fields (<0.2 T), and then recovered in the 0.2 T < H < 1.0 T region. Temperature dependence on the reverse phenomenon of the MFEs in Ph(4)C60 was clearly different from those in other linked compounds (Ph(n)C60 (n = 6, 8, 10, 12)). The present MFEs can be explained by the contribution of not only spin-lattice relaxation mechanism but also spin-spin relaxation mechanism related to {divides}2J{divides}. In time-resolved EPR measurements, the spectra in Ph(n)C60 (n = 4-12) are assigned to spin-correlated radical pairs. The methylene chain dependence of the time-resolved EPR spectra also supports the mechanism suggested in MFEs.

Original languageEnglish
Pages (from-to)242-252
Number of pages11
JournalChemical Physics
Volume334
Issue number1-3
DOIs
Publication statusPublished - Apr 20 2007

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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