Pulsed electron nuclear double resonance spectroscopy of Argonne Premium coals
Conference
·
OSTI ID:441424
- Exxon Research and Engineering Company, Annandale, NJ (United States)
Pulsed electron nuclear double resonance (ENDOR) studies on eight Argonne Premium coals are reported in this chapter. The coal samples were selected from the ranks of lignite to low-volatile bituminous. Two types of proton ENDOR signals were observed for all eight coal samples: a matrix line and local ENDOR lines. This result is in contrast to previous studies using conventional continuous-wave (CW) ENDOR techniques in which the matrix proton line dominated the spectra. Experimental conditions for recording of pulsed ENDOR spectra of coals are discussed. Local ENDOR proton hyperfine couplings of up to 20 MHz were observed, but no resolved structure was apparent in the ENDOR spectra. The magnitude of these couplings is consistent with that expected for aromatic protons on polynuclear aromatic (PNA) carbon radicals. The larger hyperfine couplings are enhanced in ENDOR spectra recorded at higher g-values as expected for PNA radicals with heteroatoms, most likely oxygen or sulfur. 5 refs., 7 figs.
- OSTI ID:
- 441424
- Report Number(s):
- CONF-891206--
- Country of Publication:
- United States
- Language:
- English
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