GROWTH AND MORPHOLOGY OF CARBON GRAINS

Carbon grains less than 1 mum in diameter have been formed in low pressure rare-gas discharges using graphite electrodes and audio frequency excitation. The grains have been examined in situ with Mie etching scattering to determine growth rates and ex situ using scanning and transmission electron microscopies to quantitatively examine their morphology. These results, as well as perturbation of the plasma impedance by the dust, suggest a dust formation mechanism based on ionization of sputtered carbon and subsequent collection of C+ ions by the Debye sheaths which surround negative particles in the plasma.