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An Nmr Study of the Occupation of C60 Interstitial Sites by Oxygen Molecules

Published online by Cambridge University Press:  25 February 2011

Roger A. Assink ,
Douglas A. Loy ,
James E. Schirber  and
Bruno Morosin
Roger A. Assink
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185
Douglas A. Loy
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185
James E. Schirber
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185
Bruno Morosin
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185
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Abstract

The 13C NMR of FCC C60 under magic angle spinning (MAS) conditionsyields linewidths on the order of 1 Hz at fields of 4.7 T. The spectrum consists of a primary resonance at 143.7 ppm and a minor peak shifted 0.7 ppm downfield. The intensity of the minor resonance relative to the primary resonance was found to vary from 0.6 to 5.5 % depending on the sample history. The downfield shift obeys Curie's law and isattributed to the Fermi contact coupling interaction between paramagnetic oxygen molecules and all 60 carbon atoms of rapidly rotating adjacent C60 molecules. Exposure of the sample to 1 kbar oxygen for 1 3/4 hours resulted in a spectrum of 7 evenly spaced resonances corresponding to 0 to 6 of the adjacent octahedral interstitial sites being filled with oxygen molecules. At ambient pressure, the oxygen diffused out of the lattice on time scales ranging from hours to days.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 270: Symposium M – Novel Forms of Carbon , 1992 , 255
Copyright
Copyright © Materials Research Society 1992

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References

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