info:eu-repo/semantics/article
High-Temperature Fluorocarbon Chemistry Revisited
Fecha
2021-07Registro en:
Cobos, Carlos Jorge; Hintzer, K.; Sölter, L.; Tellbach, E.; Morgenthaler, Annick; et al.; High-Temperature Fluorocarbon Chemistry Revisited; American Chemical Society; Journal of Physical Chemistry A; 125; 25; 7-2021; 5626-5632
1089-5639
CONICET Digital
CONICET
Autor
Cobos, Carlos Jorge
Hintzer, K.
Sölter, L.
Tellbach, E.
Morgenthaler, Annick
Troetsch, Yeicol
Resumen
The thermal dissociation reactions of C2F4and C2F6were studied in shock waves over the temperature range 1000-4000 K using UV absorption spectroscopy. Absorption cross sections of C2F4, CF2, CF, and C2were derived and related to quantum-chemically modeled oscillator strengths. After confirming earlier results for the dissociation rates of C2F4, CF3, and CF2, the kinetics of secondary reactions were investigated. For example, the reaction CF2+ CF2→ CF + CF3was identified. Its rate constant of 1010cm3mol-1s-1near 2400 K is markedly larger than the limiting high-pressure rate constant of the dimerization CF2+ CF2→ C2F4, suggesting that the reaction follows a different path. When the measurements of the thermal dissociation CF2(+Ar) → CF + F (+Ar) are extended to temperatures above 2500 K, the formation of C2radicals was shown to involve the reaction CF + CF → C2F + F (modeled rate constant 8.0 × 1012(T/3500 K)1.0exp(−4400 K/T) cm3mol-1s-1) and the subsequent dissociation C2F (+Ar) → C2+ F + (Ar) (modeled limiting low-pressure rate constant 3.0 × 1016(T/3500 K)−4.0exp(−56880 K/T) cm3mol-1s-1). This mechanism was validated by monitoring the dissociation of C2at temperatures close to 4000 K. Temperature- and pressure-dependences of rate constants of reactions involved in the system were modeled by quantum-chemistry based rate theory.