Fullerene synthesis by laser pyrolysis of hydrocarbons

A novel route for the synthesis of carbon soots containing fullerene; has been developed i.e. the pyrolysis of hydrocarbons in gas, vapour or aerosol phase, which are heated and decomposed through the absorption of IR photons emitted by a high power CW CO2 laser. Hydrocarbons such as benzene (+ cyclopentadiene), acetylene or ethylene have been tested, pure or mixed with an oxidizer agent (nitrous oxide or oxygen) and/or a sensitizer (sulfur hexafluoride). The fullerenes were identified in the soots obtained by using as precursor the benzene/oxygen or acetylene/oxygen mixture. When these compounds are produced in significant amounts they can be detected directly in the as-formed soots by Fourier Transform Infrared Spectroscopy (FTIR). For small quantities, a Soxhlet extraction procedure is necessary and th:extracts are characterized by FTIR and by other methods which are more sensitive, like mass spectrometry or High Performance Liquid Chromatography (HPLC) coupled with ultraviolet-visible spectroscopy. The influence of the operating conditions is discussed. (C) 1997 Elsevier Science Ltd.