LIF studies of iodine oxide chemistry Part 3. Reactions IO + NO3 --> OIO + NO2, I + NO3 --> IO + NO2, and CH2I + O2 --> (products): implications for the chemistry of the marine atmosphere.

DILLON, T. J.; MARIA EUGENIA TUCCERI; SANDER, ROLF; CROWLEY, J. N.

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

Año: 2008 vol. 10 p. 1540 - 1554

1463-9076

The technique of pulsed laser photolysis coupled to LIF detection of IO was used to study reactions: (R1a) IO + NO3 --> OIO + NO2; (R2) I + NO3 --> (products); (R3) CH2I + O2 --> (products); and (R4) O(3P) + CH2I2 --> IO + CH2I, at ambient temperature. Reaction (R1) was observed for the first time in the laboratory and a rate coefficient of k1 a = (9 ± 4) X 10-12cm3molecule-1 s-1obtained. For (R2), a value of k2 (298 K) = (1.0 ± 0.3) X 10-10cm3 molecule_1 s_1 was obtained, and a IO product yield close to unity determined. IO was also formed in a close-to-unity yield in reaction (R4), whereas in (R3) an upper limit of a3(IO) < 0.12 was derived.The implications of these results for the nighttime chemistry of the atmosphere were discussed.Box model calculations showed that efficient OIO formation in (R1a) was necessary to explainfield observations of large OIO/IO ratios.