Product state distribution in chemical reactions: Vibrational temperature and rotational distributions

The distributions of vibrational, rotational and translational energies in the products of atom-diatomic molecule reactions are studied on the basis of their “temperature parameters”. The validity of the vibrational temperature concept, which may characterize the variaous distributions, is examined from different points of view. The analysis is done on the basis of available data from chemiluminescence, chemical laser and molecular beams measurements and from classical trajectory calculations. All the reactions investigated are exothermic with exothermicities ranging between ≈ 17 kcal/mole and ≈ 85 kcal/mole. In most products a high degree of population inversion is found. An attempt is made to predict the complete vibrotational state distribution using the vibrational temperature only. This attempt is equivalent to the assumption that apart from the vibration, the other degrees of freedom have reached a (microcanonical) equilibrium. The agreement with experimental results is good.