Electron nuclear double resonance signals from three ingredients of coal


ELECTRON spin resonance (ESR) spectra from coals were first reported in 19541–3. Since then many ESR studies on coals have been conducted, and the signals have been shown to arise from free radicals4,5. Recently Kevan et al. studied coals using the electron nuclear double resonance (ENDOR) technique6. They detected a single-peak signal at the free proton frequency, thus providing the first direct evidence that the environments of radicals in coals contain hydrogen atoms. We report here on ENDOR signals from three ingredients which were separated out from a coal sample. The ENDOR signal from each ingredient is substantially different from that of the other ingredients. In addition, a proton hyperfine structure (hfs) was experimentally resolved, probably for the first time, for a radical in one ingredient of a coal sample.

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MIYAGAWA, I., ALEXANDER, C. Electron nuclear double resonance signals from three ingredients of coal. Nature 278, 40–41 (1979). https://doi.org/10.1038/278040a0

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