KINETICS OF THE REACTIONS OF FC(O)O RADICALS WITH NO, NO2, O-3, O(P-3), CH4, AND C2H6

Rate coefficients for the reactions of FC(O)O radicals with NO, NO2, O -3, O(P-3), CH4, and C2H6 were measured as a function of temperature a nd total pressure in the range 235-293 K and 9-210 mbar (N-2) FC(O)O r adicals were generated using the excimer laser photolysis of bis(fluor oformyl) peroxide (FC(O)OO(O)CF) at 193 nm. Time-resolved detection of FC(O)O was achieved by absorption measurements in the 3(0)(5)-band ar ound 617.5 nm using a tunable narrow band ring dye laser as a light so urce. At this wavelength the absolute decadic absorption cross section was found to be sigma(FC(O)O)(617.5) = (7.1 +/- 2.6) x 10(-18) cm(2). The following rate coefficients were determined: k(8)(FC(O)O + NO --> CO2 + FNO) = (3.8 +/- 0.5) x 10(-11) cm(3)/s, independent of temperat ure and pressure, k(9,infinity)(FC(O)O + NO2 --> products) = (5.3 +/- 1.2) x 10(-12)(T/300)(-(2.5 +/- 1)) cm(3)/s, k(11)(FC(O)O + O-3 --> pr oducts) less than or equal to 2.5 x 10(-14) cm(3)/s at 293 K, k(14)(FC (O)O + O(P-3) --> products) = (8.8 +/- 2.0) x 10(-12) cm(3)/s at 293 K , k(18)(FC(O)O + CH4 --> products) less than or equal to 4 x 10(-18) c m(3)/s at 293 K, and k(19)(FC(O)O + C2H6 --> FC(O)OH + C2H5) = (1.15 /- 0.75) x 10(-13) exp[(-1830 +/- 280 K)/T] cm(3)/s. It is concluded t hat the reactivity of FC(O)O toward these reagents resembles that of t he NO3 radical. The reactions involving NO,represent the dominant reac tive removal pathways of FC(O)O under all atmospheric conditions. Howe ver, even these reactions are not competitive with the photochemical d egradation of FC(O)O in the sunlit atmosphere. The effect of FC(O)O ch emistry on the stratospheric ozone layer is negligible.