2020-03-27T13:38:33 n2748

Kinetics of halide anions reacting with ozone

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This data set accompanies the manuscript "Gas phase reactions of iodide and bromide anions with ozone: evidence for stepwise and reversible reactions" by M. Bhujel, D.L. Marshall, A.T. Maccarone, B.I. McKinnon, A.J. Trevitt, G. da Silva, S.J. Blanksby and B.L.J. Poad.


Abstract:

Despite the impacts – both positive and negative – of atmospheric ozone for life on Earth, there remain significant gaps in our knowledge of the products, mechanisms and rates of some of its most fundamental gas phase reactions. This incomplete understanding is largely due to the experimental challenges involved in the study of gas-phase reactions of ozone and, in particular, the identification of short-lived reaction intermediates. Here we report direct observation of the stepwise reaction of the halide anions iodide (I¯) and bromide (Br¯) with ozone to produce XO3¯ (where X = I and Br, respectively). These results substantially revise the rate constant for the I¯ + O3 reaction to 1.1(±0.5) x 10-12 cm3 molecule-1 s-1 (0.13% efficiency) and the Br¯ + O3 reaction to 6.2(±0.4) x 10-15 cm3 molecule-1 s-1 (0.001% efficiency). Exploiting five-orders of temporal dynamic range on a linear ion trap mass spectrometer enabled explicit measurement of the rate constants for the highly efficient intermediate, XO¯ + O3 and XO2¯ + O3, reactions thus confirming a stepwise addition of three oxygen atoms (i.e., X¯ + 3O3 -> XO3¯ + 3O2) with the first addition representing the rate determining step. Evidence is also presented for (i) slow reverse reactions of XO¯ and XO2¯, but not the XO3¯, with molecular oxygen and (ii) the photodissociation of IO¯, IO2¯ and IO3¯ to release I¯. Collectively, these results suggest relatively short lifetimes for Br¯ and I¯ in the tropospere with direct gas-phase oxidation by ozone playing a role in both the formation of atmospheric halogen oxides and, conversely, in the ozone depletion associated with springtime polar bromine explosion events.

 

Geographical area of data collection

text
Brisbane, AU

Research areas

Ozone, halide, kinetics,

Cite this collection

Bhujel, Mahendra; Marshall, David; Maccarone, Alan; McKinnon, Benjamin; Trevitt, Adam; da Silva, Gabriel; Blanksby, Stephen; Poad, Berwyck (2020): Kinetics of Halide anions reacting with ozone. Queensland University of Technology. (Dataset) http://researchdatafinder.qut.edu.au/individual/n2748
Bhujel, Mahendra; Marshall, David; Maccarone, Alan; McKinnon, Benjamin; Trevitt, Adam; da Silva, Gabriel; Blanksby, Stephen; Poad, Berwyck (2020): Kinetics of Halide anions reacting with ozone. Queensland University of Technology. (Dataset) http://researchdatafinder.qut.edu.au/individual/n2748

Licence


Creative Commons Attribution-NonCommercial-Share Alike 4.0 (CC-BY-NC-SA)
http://creativecommons.org/licenses/by-nc-sa/4.0/

Copyright

© Queensland University of Technology, 2020

Dates of data collection

From 2018-01-01 to 2019-12-31

Connections

Has chief investigator
Berwyck Poad  (Researcher)

Contacts

Name: Dr Berwyck Poad

Other

Date record created:
2020-03-12T09:17:49
Date record modified:
2020-03-27T13:38:33
Record status:
Published - Open Access