Shock-tube measurement of nitridation coefficient of solid carbon

Abstract

The coefficient of reaction of nitrogen atoms with solid carbon to form gaseous cyanogen CN is measured in a shock tube. A stream of highly dissociated nitrogen is produced in a shock tube and passed over a grid of metal wire coated with carbon. The radiation emitted by the wake of the wire grid is observed with a monochromator set at 386 nm, where CN is known to radiate strongly. From the intensity of the CN radiation, the concentration of CN in the wake is determined. The concentration of nitrogen atoms in the stream are calculated by integrating conservation equations. From these concentration values, the fraction of the collisions of nitrogen atoms producing CN, that is, the reaction coefficient, is deduced. The results show that the reaction coefficient is about 0.3 at both 300 and 1100 K. The uncertainties in the results are described, and improvements are proposed.