The Pulse Radiolysis of Deaerated Aqueous Bromide Solutions<sup>1</sup>

Matheson, Max S.; Mulac, William A.; Weeks, James L.; Rabani, Joseph

doi:10.1021/j100879a004

Cited by 105 publications

(78 citation statements)

References 12 publications

(21 reference statements)

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“…Again, the recent determination by Kwon [49] is smaller than the classical determination by Zehavi and Rabani. [60] The reason for the discrepancy between both studies could be the pH dependency of the reaction rate constant as described in Matheson et al [61] 2.4. Review of the SCN À Competition Kinetic Reference System…”

Section: Inorganic Compoundsmentioning

confidence: 96%

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

et al. 2010

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The most important radicals which need to be considered for the description of chemical conversion processes in tropospheric aqueous systems are the hydroxyl radical (OH), the nitrate radical (NO(3)) and sulphur-containing radicals such as the sulphate radical (SO(4)(-)). For each of the three radicals their generation and their properties are discussed first in the corresponding sections. The main focus herein is to summarize newly published aqueous-phase kinetic data on OH, NO(3) and SO(4)(-) radical reactions relevant for the description of multiphase tropospheric chemistry. The data compilation builds up on earlier datasets published in the literature. Since the last review in 2003 (H. Herrmann, Chem. Rev. 2003, 103, 4691-4716) more than hundred new rate constants are available from literature. In case of larger discrepancies between novel and already published rate constants the available kinetic data for these reactions are discussed and recommendations are provided when possible. As many OH kinetic data are obtained by means of the thiocyanate (SCN(-)) system in competition kinetic measurements of OH radical reactions this system is reviewed in a subchapter of this review. Available rate constants for the reaction sequence following the reaction of OH+SCN(-) are summarized. Newly published data since 2003 have been considered and averaged rate constants are calculated. Applying competition kinetics measurements usually the formation of the radical anion (SCN)(2)(-) is monitored directly by absorption measurements. Within this subchapter available absorption spectra of the (SCN)(2)(-) radical anion from the last five decades are presented. Based on these spectra an averaged (SCN)(2)(-) spectrum was calculated. In the last years different estimation methods for aqueous phase kinetic data of radical reactions have been developed and published. Such methods are often essential to estimate kinetic data which are not accessible from the literature. Approaches for rate constant prediction include empirical correlations as well as structure activity relationships (SAR) either with or without the usage of quantum chemical descriptors. Recently published estimation methods for OH, NO(3) and SO(4)(-) radical reactions in aqueous solution are finally summarized, compared and discussed.

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Section: Inorganic Compoundsmentioning

confidence: 96%

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

et al. 2010

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“…[33][34][35][36][37] The OH radical formed from the O À reaction 58 with H 2 O oxidizes Br À and Cl À to form Br 2 , Cl 2 and BrCl. 30,[59][60][61][62][63][64][65][66][67][68][69][70][71] These reactive halogen gases play a significant role in the chemistry and composition of the marine boundary layer (MBL). 45,[72][73][74][75][76][77][78][79][80][81] In the coastal MBL, the photochemical cycling of chlorine enhances tropospheric ozone, whereas gaseous bromine species cause ozone destruction during polar sunrise in polar regions 75,76,[82][83][84][85] as well as in midlatitudes.…”

Section: Introductionmentioning

confidence: 99%

Production of gas phase NO2 and halogens from the photolysis of thin water films containing nitrate, chloride and bromide ions at room temperature

Richards-Henderson

Callahan

Nissenson

et al. 2013

Phys. Chem. Chem. Phys.

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aNitrate and halide ions coexist in particles generated in marine regions, around alkaline dry lakes, and in the Arctic snowpack. Although the photochemistry of nitrate ions in bulk aqueous solution is well known, there is recent evidence that it may be more efficient at liquid-gas interfaces, and that the presence of other ions in solution may enhance interfacial reactivity. This study examines the 311 nm photolysis of thin aqueous films of ternary halide-nitrate salt mixtures (NaCl-NaBr-NaNO 3 ) deposited on the walls of a Teflon chamber at 298 K. The films were generated by nebulizing aqueous 0.25 M NaNO 3 solutions which had NaCl and NaBr added to vary the mole fraction of halide ions. Molar ratios of chloride to bromide ions were chosen to be 0.25, 1.0, or 4.0. The subsequent generation of gas phase NO 2 and reactive halogen gases (Br 2 , BrCl and Cl 2 ) were monitored with time. The rate of gas phase NO 2 formation was shown to be enhanced by the addition of the halide ions to thin films containing only aqueous NaNO 3 .] r 1.0, the NO 2 enhancement was similar to that observed for binary NaBr-NaNO 3 mixtures, while with excess chloride NO 2 enhancement was similar to that observed for binary NaCl-NaNO 3 mixtures. Molecular dynamics simulations predict that the halide ions draw nitrate ions closer to the interface where a less complete solvent shell allows more efficient escape of NO 2 to the gas phase, and that bromide ions are more effective in bringing nitrate ions closer to the surface. The combination of theory and experiments suggests that under atmospheric conditions where nitrate ion photochemistry plays a role, the impact of other species such as halide ions should be taken into account in predicting the impacts of nitrate ion photochemistry.

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“…The OH radicals thus produced react with Rr-ions within lo-% to form Br atoms. At the high concentration of Br-used, the forward reaction of the equilibrium Br + Br-Br2-was completed within about 20 ns, and the contribution of the back reaction was practically negligible [3]. About 100 ns after the pulse, excited pyrene molecules and Br2-radical anions were present a t known concentrations, and their reaction could be monitored subsequently by optical absorption measurements.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of the heterogeneous electron transfer reaction of triplet pyrene in micelles to Br₂⁻ radicals in aqueous solution

Frank¹,

Grätzel²,

Henglein³

et al. 1976

Int J of Chemical Kinetics

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A combined flash photolysis and pulse radiolysis experiment was carried out to produce triplet pyrene (P) molecules in micelles of cetyltrimethylammonium bromide and Brt-in the surrounding aqueous medium. The reaction 3Pmie + Bryaq + PA,c + 2 Br-was followed by optical absorption measurements in the 10-8-10-4-sec range. This reaction possesses a "fast" and a "slow" component wit.h respective rate constants of 2.3 X lo6 sec-l and 1 X 109.M-1 . sec-l.The fast component is related to the probability of a Brq-radical meeting a triplet pyrene containing micelle on the first encounter (only lSyc of the micelles contained a triplet. molecule). Reactions involving more than one Brq-radical-micelle encounter are ascribed to the slow component. The presence of two components reflects the fact, that the residence time of a Brl-radical in the vicinit,y of a cationic micelle is substantially longer than the diffusion time of the radical between micelles. Thus the conditions met in micellar chemistry differ dramatically from those in ordinary solution kinetics where the encounter time is generally much shorter than the time between encounters. Some considerations on the energet.ics of this electron transfer reaction are also presented.

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The Pulse Radiolysis of Deaerated Aqueous Bromide Solutions¹

Cited by 105 publications

References 12 publications

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

Production of gas phase NO2 and halogens from the photolysis of thin water films containing nitrate, chloride and bromide ions at room temperature

Kinetics of the heterogeneous electron transfer reaction of triplet pyrene in micelles to Br₂⁻ radicals in aqueous solution

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The Pulse Radiolysis of Deaerated Aqueous Bromide Solutions1

Cited by 105 publications

References 12 publications

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

Tropospheric Aqueous‐Phase Free‐Radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools

Production of gas phase NO2 and halogens from the photolysis of thin water films containing nitrate, chloride and bromide ions at room temperature

Kinetics of the heterogeneous electron transfer reaction of triplet pyrene in micelles to Br2− radicals in aqueous solution

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The Pulse Radiolysis of Deaerated Aqueous Bromide Solutions¹

Kinetics of the heterogeneous electron transfer reaction of triplet pyrene in micelles to Br₂⁻ radicals in aqueous solution