  Rate constants for the N + C2 reaction have been measured in a continuous
supersonic flow reactor over the range 57 K to 296 K by the relative rate
technique employing the N + OH - H + NO reaction as a reference. Excess
concentrations of atomic nitrogen were produced by the microwave discharge
method and C2 and OH radicals were created by the in-situ pulsed laser
photolysis of precursor molecules C2Br4 and H2O2 respectively. In parallel,
quantum dynamics calculations were performed based on an accurate global
potential energy surfaces for the three lowest lying quartet states of the C2N
molecule. The 14A" potential energy surface is barrierless, having two deep
potential wells corresponding to the NCC and CNC intermediates. Both the
experimental and theoretical work show that the rate constant decreases to low
temperature, although the experimentally measured values fall more rapidly than
the theoretical ones except at the lowest temperatures. Astrochemical
simulations indicate that this reaction could be the dominant source of CN in
dense interstellar clouds.
