Multiphoton excitation and dissociation of DN3 by short CO2 laser pulses is shown to be a collisionless process. The characteristic features of this multiphoton process are systematically studied. The average number of photons absorbed per DN3 molecule and the absolute dissociation yield show a strong dependence on the peak laser intensity. Resonantly enchanced coherent multiphoton excitation, rather than stepwise incoherent excitation, is suggested. The primary dissociation products of DN3 are ND[1delta] and N2. Formation of vibrationally excited ND[1delta] intermediates is suggested. The reactions of ND[1delta] with DN3 lead to chemiluminescent signals originating from the formation of electronically excited ND2[2A1] and ND[3II]. Formation of the ND[3II] intermediate is attributed to a reaction of ND[1delta] and vibrationally excited DN3 molecules: ND[1delta]+DN3-ND[3II]+ND[3-]+N2.