This work presents a theoretical and experimental investigation of the dissociation rate and N(S-4) atom concentrations in a nitrogen DC discharge operating at gas pressures p = 0.5-4 Torr and discharge currents I = 10-80 mA. By comparing the measured and calculated atomic densities, the various mechanisms for production of N(S-4) atoms are discussed and weighted. It is shown that electron impact dissociation controls nitrogen dissociation only at the lower pressures considered in this study. For p greater than or similar to 1 Torr, dissociation proceeds essentially via reactions involving the long-lived metastable heavy-particles N-2(X (1)Sigma(g)(+), v) and N-2(A (3)Sigma(u)(+)), such as 2N(2)(X, 10 < v < 25) --> N2(X) + 2N and N-2(X-1 14 less than or equal to v' less than or equal to 19) + N-2(A) --> N-2(X) + 2N. For a gas temperature of 500 K, the rate coefficients for these two reactions are estimated to be of the order of 10(-15) and 10(-12) cm(3)/s, respectively. (C) 2003 Elsevier Science B.V. All rights reserved.