Spin-mapping of coal structures with ESE and ENDOR
Work reported this quarter (1) continues the study of organic sulfur species in coal with Very High Frequency (VHF) EPR spectroscopy and (2) includes some pulsed EPR work on coals carried out with the S-band ESE spectrometer. A detailed VHF study of one coal from the Illinois Coal Sample Bank is reported, including spectra from separated macerals and solvent extracted coal. Further refinements in the two-species model for interpreting these spectra are presented. It is increasingly apparent that while the organic sulfur species seen by VHF EPR in coal may be thiophenic, they do not have spectra that directly implicate either thiophene or dibenzothiophene as unique molecular forms. The emerging picture seems to indicate a thiophenic sulfur species in which the unpaired electron is delocalized over a more extensive aromatic cluster. VHF EPR may be quite specific for aromatic organic sulfur. Spectra from eight coals in the Argonne Premium Sample program also have been studied by VHF EPR, and analysis is now under way to determine how well the two-species model accounts for the general features of these spectra. Pulsed electron spin resonance has been performed on the Argonne coals in order to determine their electron phase memory times (T{sub M}) at ca. 1000 G magnetic fields. EPR and NMR imaging experiments on Illinois coals are currently focussing on developing better resolution through improvements in the spectrometer hardware. 18 refs., 10 figs., 2 tabs.
- Research Organization:
- Illinois Univ., Urbana, IL (USA)
- Sponsoring Organization:
- DOE/FE
- DOE Contract Number:
- FG22-88PC88921
- OSTI ID:
- 6409310
- Report Number(s):
- DOE/PC/88921-6; ON: DE91004342
- Country of Publication:
- United States
- Language:
- English
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Spin-mapping of coal structures with ESE and ENDOR
Spin-mapping of coal structures with ESE and ENDOR
Related Subjects
010600* -- Coal
Lignite
& Peat-- Properties & Composition
656002 -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AROMATICS
CARBONACEOUS MATERIALS
COAL
DOCUMENT TYPES
ENDOR
ENERGY SOURCES
FOSSIL FUELS
FUELS
MACERALS
MAGNETIC RESONANCE
MATERIALS
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PROGRESS REPORT
RESONANCE
SPECTRA
SPECTROSCOPY
SPIN ECHO
VITRINITE