Electron-spin resonance of stable radicals in Langmuir-Blodgett films of a merocyanine dye: Study of hyperfine coupling using a enriched15 dye

Shin Ichi Kuroda, Keiichi Ikegami, Yuka Tabe, Kazuhiro Saito, Mitsuyoshi Saito, Michio Sugi

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Two kinds of stable radical species exist in mixed Langmuir-Blodgett (LB) films of a merocyanine dye and arachidic acid. One of the species exhibits clear nitrogen hyperfine structure in ESR spectra, which was previously confirmed by measurements at X and Q bands. Use of the enriched15 dye derivative clearly identified the hyperfine coupling to arise from the nitrogen nucleus in benzothiazole, which belongs to the chromophore of the dye molecule; N-C"C-C"C-C"O. ESR spectra measured at both X and K bands in unsubstituted and substituted15 systems permits the detailed analysis of in-plane molecular orientation using the spectrum-simulation method incorporating three-dimensional freedom of orientation. The analysis of the dependence of the spectra on the substrate position yields the local orientation of the radical molecules, which shows a higher degree of orientation toward the edge of the substrate. This behavior coincides with that of the majority of molecules forming J aggregates, obtained from optical analysis, and is well described by a recent theory of the flow orientation of molecular domains caused during the dipping process of LB films. This coincidence between the orientation of the radicals and J aggregates provides new evidence that stable radicals are generated in the J aggregate. The mechanism of radical generation is discussed in view of our previously proposed model of an intermolecular charge transfer in J aggregates.

Original languageEnglish
Pages (from-to)2531-2540
Number of pages10
JournalPhysical Review B
Volume43
Issue number4
DOIs
Publication statusPublished - 1991
Externally publishedYes

Fingerprint

Langmuir Blodgett films
Langmuir-Blodgett films
Paramagnetic resonance
electron paramagnetic resonance
Coloring Agents
Dyes
dyes
Molecules
Nitrogen
superhigh frequencies
Molecular orientation
Substrates
Chromophores
Charge transfer
nitrogen
molecules
extremely high frequencies
Derivatives
dipping
hyperfine structure

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Electron-spin resonance of stable radicals in Langmuir-Blodgett films of a merocyanine dye : Study of hyperfine coupling using a enriched15 dye. / Kuroda, Shin Ichi; Ikegami, Keiichi; Tabe, Yuka; Saito, Kazuhiro; Saito, Mitsuyoshi; Sugi, Michio.

In: Physical Review B, Vol. 43, No. 4, 1991, p. 2531-2540.

Research output: Contribution to journalArticle

Kuroda, Shin Ichi ; Ikegami, Keiichi ; Tabe, Yuka ; Saito, Kazuhiro ; Saito, Mitsuyoshi ; Sugi, Michio. / Electron-spin resonance of stable radicals in Langmuir-Blodgett films of a merocyanine dye : Study of hyperfine coupling using a enriched15 dye. In: Physical Review B. 1991 ; Vol. 43, No. 4. pp. 2531-2540.
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