The Novel Use of On-Line Diagnostics for the Improved Production of Fullerenes
University of New Brunswick
Fullerenes, discovered in 1985, are known to form naturally in carbon-rich conditions and consequently can exist in nature and throughout the universe. Using simple characterization techniques, researchers were able to detect fullerenes in planetary nebulae. Interstellar space provides near ideal conditions to use spectroscopy, with minimal interference and low temperatures providing high signal to background, narrow peak width and well-defined energy transitions. At low pressure conditions (<1 MPa), fullerenes sublime directly to gas phase with a vapour pressure related to temperature. Fullerene vapour was generated in a tube furnace at 300oC-800oC under vacuum as a high temperature simulation of fullerenes in space. By monitoring fullerene abundance using infrared radiation spectroscopy (IRS) and using known thermal emission transitions, significant trends were noticed where peak intensity and area were dependent on temperature and, therefore, fullerene vapour pressure. The Applied Nano-Lab at UNB has constructed and operated a 3-phase AC plasma reactor to produce fullerenes. The oven studies under vacuum were applied to the 3-phase reactor as an on-line fullerene detector. An attempt was made to correlate mass flow rate of feedstock and volumetric flow rate of plasma gas to fullerene detection and yield.