Production of Vanadium–Carbon Clusters Using DC Arc Discharges with Pulsed Helium/Methane Gas Injection

Abstract

Experimental studies of the synthesis of new types of vanadium–carbon clusters have been carried out using dc arc discharges, where a pair of graphite rods mixed with the vanadium carbide (VC) powders were used as the electrodes. A high-pressure pulsed gas injection technique, where pulsed He gases were periodically injected into the dc arc plasma to cool the excited carbon and vanadium atoms, was used. The effect of an addition of carbon atoms on cluster production was also examined by injecting pulsed CH4 gases in addition to high-pressure He gas pulses. The soots produced in the dc arc discharges were analyzed using a laser desorption reflectron type time-of-flight (TOF) mass spectrometer. Experimental results show that when CH4 gas was added to He gas with a partial pressure of 15%, enhanced VnC2n clusters with a VC2-mass spacing of Δm/z=75 were detected in the mass range of 225<m/z<675. Experiments show that these vanadium–carbon clusters are formed by the vanadium atoms evaporated from the electrodes and the carbon atoms supplied from the injected CH4 gas.