The effects of the vacuum sublimation process on the composition of C60/C70 films

Thermogravimetric (TG) analysis was carried out under atmospheric condition for C60/C70 powder mixture separated from soot by benzene Soxhlet extraction. The result indicates that the starting temperature for obvious sublimation of C60 is about 600 C. The powder mixture was sublimated under various technology conditions in high vacuum to prepare films on KBr crystal substrates. Fourier transform IR (FTIR) spectra of the films, the powder mixture and pure C60 powder separated by chromatography reveal that the composition of films depends upon the experimental procedure and that pure C60 film can be obtained under optimum process conditions. (orig.)