Density of fullerene containing soot as determined by helium pycnometry

Mass-spectrometric techniques have demonstrated the presence of carbon clusters C2n with n as high as 300, in carbon soot material produced using the "arc-synthesis" method. While new techniques are being explored for solvation of larger fullerene cages, beyond the more conventional solvation of the "smaller" fullerene molecules such as C60 and C70, the question arises: how much of the soot is fullerene cage molecules? One expects the density of fullerene soot composed of, say, C240 and larger cages, to be significantly less than graphite, 2.2670 g cm-3, and also less than C60, 1.65 g cm-3. The helium pycnometry determined density of a sample of commercially available raw "fullerene" soot is 1.5651 g cm-3. It is likely that this is an upper bound to the density, due to permeation by helium resulting from the large size of some fullerenes present in the soot. © 1991.