FTIR-Spectroscopic Study of Reactions of FCO and FC(O)OO Radicals in the Presence of O_2 and NO_2

摘要

Steady-state photolysis of oxalylfluoride (FC(O)C(O)F) together with FTIR-spectroscopy has been used to investigate the reactions of FCO and FC(O)OO radicals in the presence of O_2 and NO_2. Formation of FCO radicals has been identified as the main photodissociation process of oxalylfluoride at λ = 254 nm. However, a quantum yield of φ = 0.11 ±0.02 was attributed to the direct formation of CF_2O and CO in this process. In the presence of O_2, the products of reactions of FC(O)O_x(x = 0,1,2) radicals were bis-fluoroformylperoxide (FC(O)OOC(O)F) and bis-fluoroformyltrioxide (FC(O)OOOC(O)F), as well as CF_2O, CO and CO_2. Addition of NO_2 to the reaction system led to the formation of fluoroformylperoxynitrate (FC(O)OONO_2). The rate constant for the thermal decomposition of fluoroformylperoxynitrate in the temperature range 275 - 307 K was measured to be k(T) = 3.5 x10~(16)exp(-13900_(-2600)~(+1700)/T)s~(-1). For bis-fluoroformyltrioxide, a rate constant for thermal decomposition of 6.0 x10~(-4) s~(-1) was measured at temperatures around 250K. The thermal stability of bis-fluoroformyltrioxide and fluoroformylperoxynitrate is discussed in terms of a comparison with the stability of similar molecules.