Intra and intermolecular energy transfer in thermal dissociation in the gas and liquid N2O4

Molecular dynamics simulations were performed for the dissociation and association (D/A) reactions N 2 O 4 2NO 2 in the gas and liquid phases. The transition state of the D/A reactions was identified as the phase space surface E T =0, where E T is the sum of the potential and kinetic energies of the interfragment motion. The dissociation reaction in liquid N 2 O 4 is found to occur by two steps: first, a reactant is activated by intermolecular energy transfer from solvent to reactant, and second, the dissociation occurs by energy transfer from intrafragment vibrational and rotational modes to interfragment translational mode. The association reaction proceeds by two steps: interfragment translational energy of an encounter NO 2 pair is transferred to intrafragment modes and then the associated N 2 O 4 is deactivated by intermolecular energy transfer from product to solvent.