Application of unimolecular reaction rate theory for highly flexible transition states to the dissociation of NCNO into NC and NO

Abstract

A recently described method for implementing RRKM theory for unimolecular reactions with highly flexible transition states is applied to the calculation of energy and angular momentum resolved rate constants and rotational–vibrational energy distributions for the reaction NCNO→hν NCNO*→NCNO(vib. hot)→NC+NO. The dissociation rate results are compared to the recent experimental results of Khundkar et al., and the vibrational and rotational distribution results are compared to the experimental values of Nadler et al. Comparison is also made with phase space theory calculations. The calculated rotational distributions at energies below the vibrational threshold of the products are the same as those of PST. At energies (2348, 2875 cm−1) above this threshold energy the rovibrational distribution is in better agreement with the data than is that of PST. The need for obtaining more accurate ab initio potential energy surfaces is noted, particularly for treating reactions at still higher energies.