X. Y. Chang, T. D. Sewell, Donald L. Thompson and Lionel M. Raff
J. Chem. Phys. 97, 7354 (1992)
Abstract
In the present paper, we have explored the classical power spectrum method to study the statistical and non-statistical behavior shown in unimolecular dissociative dynamics. We chose two system to study: 1,2-difluoroethane, which is refereed as a non-RRKM system by several previous studies[1,2,3], and 2-chloroethyl radical[1,4], which is, in contrast, a RRKM system. The spectra are generated for both system at varuios initial conditions and different energies. We found that a statistical RRKM system is always accompanied by the significant coupling between the different type mode, for example, stretching mode and non-stretching mode. This kind of strong coupling is normally absent in a non-RRKM system. Furthermore, it was also found that for a RRKM system, the Power spectrum generated for a superposition of all internal coordinates (SIC) shows a complete ergotic behavior, while SIC spectrum for non-RRKM system remains its normal mode identity even at the energy well above bond fission energy. It is, therefore, believed that Power spectrum is an effective and explicit technique to anticipate the behavior of a unimolecular dissociative reaction being statistical or non-statistical prior to the reaction.