Kinetics of the reactions of iodine monoxide radicals with nitric oxide and nitrogen dioxide

Daykin, Edward; Wine, P. H.

doi:10.1021/j100374a034

Cited by 29 publications

(37 citation statements)

References 11 publications

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“…Iodine crystals had a stated minimum purity of 99.999%. Procedures for purifying NO, preparing and purifying NO2, and handling 12 were identical to those described previously [Daykin and Wine, 1990]. Dimethylsulfide was Aldrich anhydrous grade, packaged under nitrogen, with a stated purity of 99+%.…”

Section: -0 Band Of the Iomentioning

confidence: 82%

“…The kinetics of the IO + DMS reaction were investigated by monitoring the temporal profile of IO following 351-nm laser flash photolysis of I2/NO2/DMS/N2/O 2 mixtures. A schematic of the laser flash photolysis-long-path absorption apparatus and description of the reaction cell can be found elsewhere [Wine et al, 1988], as can a detailed description of the IO detection system [Daykin and Wine, 1990]. Experimental details pertinent to this study are discussed below.…”

Section: Experimental Techniquementioning

confidence: 93%

“…under the experimental conditions employed in this study, i.e., bath gas pressures of 40 to 300-Torr N 2 + 02 and reaction times longer than 0.25 ms, vibrational relaxation of IO occurs much more rapidly than does chemical reaction[Daykin and Wine, 1990].Reaction mixtures employed to study (t' represents a time shortly after the laser fired when IO production was complete but little or no IO decay had occurred; t" represents a time after IO removal had gone to completion but before more stable species, destroyed or produced as a result of the laser flash, diffused or flowed out of the detection volume; St represents the signal level at time t, and k5 represents the first-order rate coefficient for the process (R5)IO-• loss by reaction with background impurities and diffusion and/or flow out of the detection zoneRESULTS AND DISCUSSIONAll experiments were carried out at room temperature, 298 + 2 K. Before initiating laser flash photolysis kinetics experiments, preliminary studies were carried out to demonstrate that NO 2, 12, DMS, N 2, and 02 could be mixed and flow through the reaction cell without the occurrence of significant chemical change due to dark reactions. In one experiment, a mixture containing 1 x 1015 NO 2 cm -3 and 1 x 1015 12 cm -3 in 100-torr air was flowed through the system, and both NO 2 and 12 were monitored by UV-visibleUnder the conditions of our experiments, k4[NO 2] >> ks.Todetermine k•, pseudo first-order IO decay rates were measured as a function of [DMS] at constant [NO2].…”

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confidence: 99%

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Rate of reaction of IO radicals with dimethylsulfide

Daykin¹,

Wine²

1990

J. Geophys. Res.

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The kinetics of the title reaction have been investigated at 298 K using time‐resolved long‐pathlength absorption spectroscopy to monitor the temporal behavior of IO following 351‐nm laser flash photolysis of NO2/I2/CH3SCH3(DMS)/N2/O2 mixtures. We obtain an upper limit bimolecular rate constant for the IO+DMS reaction of 3.5×0−14 cm3 molecule−1 s−1; this upper limit is nearly 3 orders of magnitude slower than two previously reported measurements. Our results suggest that coupling of the marine sulfur and iodine cycles via the IO+DMS reaction is negligible.

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Section: -0 Band Of the Iomentioning

confidence: 82%

Section: Experimental Techniquementioning

confidence: 93%

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confidence: 99%

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Rate of reaction of IO radicals with dimethylsulfide

Daykin¹,

Wine²

1990

J. Geophys. Res.

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“…IO radicals were produced by photolyzing a mixture of I 2 /N 2 O at 193 nm at pressures between 5 and 100 Torr in N 2 and temperatures between 240 and 370 K. They reported pressure independent kinetics and an Arrhenius expression of k(T) IO+NO ¼ (1.02 AE 0.31) Â 10 À11 exp[(185 AE 70) K/T] cm 3 s À1 corresponding to k IO+NO (298 K) ¼ (1.92 AE 0.07) Â 10 À11 cm 3 s À1 . Daykin et al 30 investigated this reaction by photolyzing a mixture of NO 2 /I 2 at 351 nm as a photochemical IO precursor. The temporal profiles of the IO radicals were observed by long path absorption spectroscopy in an excess of NO.…”

Section: Methodsmentioning

confidence: 99%

LIF study of the reactions of the IO radical with NO and NO2 over an extended range of temperature and pressure

Hölscher

Zellner

2002

Phys. Chem. Chem. Phys.

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A pulsed laser-photolysis / pulsed laser induced fluorescence technique was used to investigate the kinetics of the reactions of the IO radical with NO and NO 2 . For the reaction (1) IO + NO ! I + NO 2 the rate constants between 233 and 346 K were found to be k IO+NO (T) ¼ (4.3 AE 1.0) Â 10 À12 exp[(397 AE 65) K/T] cm 3 s À1 , independent of pressure between 13 and 130 mbar as measured at 286 K. Reaction (2) IO + NO 2 + M ! IONO 2 + M has been studied between 48 and 402 mbar in the temperature range 238-298 K. The rate constants were found to be in the fall-off region between second-and third-order kinetics for this pressure range. Assuming a broadening factor of F C ¼ 0.6, independent of temperature, a set of fall-off parameters with k 0 (T) ¼ 4.1 Â 10 À31 (T/298 K) À6.3 cm 6 s À1 and k 1 ¼ 1.0 Â 10 À11 cm 3 s À1 was found to adequately describe the data.

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“…HI and HOI are formed from the reaction of I and IO with HO 2 free radicals respectively. [15][16][17] IONO 2 is formed from the association of IO with NO 2 : 16,18…”

Section: Introductionmentioning

confidence: 99%