Influence of Molecular Parameters on Rate Constants of Thermal Dissociation/Recombination Reactions: The Reaction System CF4 ⇄ CF3 + F.

The possibilities to extract incompletely characterized molecular parameters from experimental thermal rate constants for dissociation and recombination reactions are explored. The reaction system CF4 (+M) ⇄ CF3 + F (+M) is chosen as a representative example. A set of falloff curves is constructed and compared with the available experimental database. Agreement is achieved by minor (unfortunately not separable) adjustments of reaction enthalpy and collisional energy transfer parameters.

The Thermal Dissociation-Recombination Reactions of SiF4, SiF3, and SiF2: A Shock Wave and Theoretical Modeling Study.

Monitoring UV absorption signals of SiF2 and SiF, the thermal dissociation reactions of SiF4 and SiF2 were studied in shock waves. Rationalizing the experimental observations by standard unimolecular rate theory in combination with quantum-chemical calculations of the reaction potentials, rate constants for the thermal dissociation reactions of SiF4, SiF3, and SiF2 and their reverse recombination reactions were determined over broad temperature and pressure ranges. A comparison of fluorosilicon and fluorocarbon chemistry was finally made.