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Generation of C 6 0 at a rate of more than 10 grams per day has been accomplished by operation of a carbon arc in an atmosphere of helium. Optimum yield of 15% was found to occur near 100-200 torr, but yields greater than 3% were found throughout the range between 50 and 760 torr.A model is proposed to explain the observed behavior based on competition between annealing of graphitic sheets to curve so that they minimize dangling bonds, and further rapid growth of these sheets in the gas phase to form giant fullerenes. In agreement with predictions of this model, laser vaporization of graphite targets was found to produce macroscopic quantities of C 6 0 only when performed in an oven above 1000 C.

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