Rate parameters for reactions of ground-state difluorocarbene and determination of the absolute intensity of the Ã1B1–X1A1 absorption bands

Abstract

An effective extinction coefficient (to base 10) of 7620 ± 400 l. mole^–1 cm^–1 at 298°K was derived for the band maximum of CF₂ at 249 nm, by measuring the intensity of the Ã(¹B₁)–X(¹A₁) system after flash photolysis of NO₂ in mixtures containing C₂F₄ and N₂. The oscillator strength of the transition was 0.028 ± 10%. The decay of CF₂ was studied in flashed C₂F₄+ N₂ and CF₂CFCl + N₂ mixtures and rate parameters for the dimerization were recorded: k₁=(2.5 ± 0.5)10⁶T^½ exp(–200 ± 50/T(°K))l. mole^–1 sec^–1. An approximate rate constant for reaction of CF₂ with CFCl at 298°K is 6(± 5)10⁸ l. mole^–1 sec^–1. Data for the reaction (2) of CF₂ with C₂F₄ were combined with the value for k₁, to obtain k₂=(8.7)10⁴T^½ exp(–3200 ± 625/T(°K))l. mole^–1 sec^–1.