Vapor pressure of Buckminsterfullerene

The vapor pressures of the fullerenes C60 and C70 have been measured over the temperature range 400–600 °C by the Knudsen-effusion thermogravimetric technique. For C60, a heat of sublimation of 38±1 kcal/mol is obtained, and the value for C70 is 45±1 kcal/mol. The vapor pressure of C60 ranges from 1.8×10−5 and 1.4×10−2 Torr and that of C70 is between 1.4×10−5 and 8.7×10−3 Torr over the temperature range investigated. At 500 °C, the vapor pressure of C60 is about 1035 that of graphite. The entropy of vaporization of C60 obeys Trouton’s rule.