Vibrational Energy Transfer Modeling of Nonequilibrium Polyatomic Reaction Systems

Abstract

The use of energy transfer data and models in describing nonequilibrium polyatomic reaction systems is discussed with particular emphasis on the information needed for modeling vibrational energy transfer. In the discussion, it is pointed out that key areas of energy transfer knowledge are still lacking and the available experimental data are limited in scope and are of uneven quality. Despite these limitations, it is still possible to carry out meaningful simulations of chemical systems in which vibrational energy transfer is important. The vibrational energy master equation, which is the basis for modeling, and various experiments and calculations that provide the basis for practical energy transfer models and parametrizations are described. Two examples of gas phase reaction systems are presented in which vibrational energy transfer is important. The decomposition of norbornene shows how energy transfer parameters can be obtained from measurements of shock-induced chemical reactions, but even the best such experiments provide only limited information about energy transfer. Chemically activated 2-methylhexyl radicals illustrate the complex reactions of multiple isomers connected by multiple isomerization pathways and reacting according to multiple decomposition pathways.

The Reaction Kinetics of Amino Radicals with Sulfur Dioxide

“…Figure 3 shows the good agreement with experiment obtained with the choice of ⟨Δ ⟩ down = 350 cm −1 and the exponential model for energy transfer. This value of ⟨Δ ⟩ down corresponds [27] to an overall average energy transferred in all up and down transitions ⟨Δ ⟩ of about −2.4 kJ mol −1 at 298 K, and a collisional efficiency c = 0.4, which are typical for unimolecular reactions in Ar bath gas as summarized by Troe [28]. Thus our observations at the low-pressure limit may be rationalized in terms of the PES.…”

Recent Advances in Development and Applications of the Mixed Quantum/Classical Theory for Inelastic Scattering

“…This phase is then accounted for simply by multiplying the final computed probability amplitude by the phase factor: . Such corrected probability amplitude can be used to compute the elastic scattering total cross section: (20) and the differential scattering amplitude (needed in calculations of the differential cross section 60 ): (21) where is the Legendre polynomial of th degree. Note that this method can be applied to the inelastic scattering channels as well, but the total inelastic cross sections are insensitive to phases, because probability amplitudes are squared before any other operations in eq…”

Computational Studies of Intramolecular Hydrogen Atom Transfers in the β-Hydroxyethylperoxy and β-Hydroxyethoxy Radicals

“…61 The bath gas was N 2 at 298 K, with Lennard-Jones parameters of σ ) 3.74 Å and ) 82 K. 62,63 Following the same procedures [64][65][66][67] used in our study of isoprene ozonolysis, 68 we estimated Lennard-Jones parameters of σ ) 4.31 Å and ) 297 K for the •C 2 H 5 O 3 minima and transition structures.…”