Laser induced fluorescence studies of iodine oxide chemistry Part II. The reactions of IO with CH3O2, CF3O2 and O3

The technique of pulsed laser photolysis was coupled to laser induced fluorescence detection of iodine oxide (IO) to measure rate coefficients, k for the reactions IO + CH3O2 -> products (R1, 30-318 Torr N-2), IO + CF3O2 -> products (R2, 70-80 Torr N2), and IO + O-3 -> OIO + O-2 (R3a). Values of k(1) = (2 +/- 1) x 10(-12) cm(3) molecule(-1) s(-1), k(2) = (3.6 +/- 0.8) x 10(-11) cm(3) molecule(-1) s(-1), and k(3a) < 5 x 10(-16) cm(3) molecule(-1) s(-1) were obtained at T = 298 K. In the course of this work, the product yield of IO from the reaction of CH3O2 with I was determined to be close to zero, whereas CH3OOI was formed efficiently at 70 Torr N-2. Similarly, no evidence was found for IO formation in the CF3O2 + I reaction. An estimate of the rate coefficients k(CH3O2 + I) = 2 x 10(-11) cm(3) molecule(-1) s(-1) and k(CH3OOI + I) = 1.5 x 10(-10) cm(3) molecule(-1) s(-1) was also obtained. The results on k(1)-k(3) are compared to the limited number of previous investigations and the implications for the chemistry of the marine boundary layer are briefly discussed.