Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.414 IF 5.414
  • IF 5-year value: 5.958 IF 5-year
    5.958
  • CiteScore value: 9.7 CiteScore
    9.7
  • SNIP value: 1.517 SNIP 1.517
  • IPP value: 5.61 IPP 5.61
  • SJR value: 2.601 SJR 2.601
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 191 Scimago H
    index 191
  • h5-index value: 89 h5-index 89
Preprints
https://doi.org/10.5194/acp-2020-456
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-2020-456
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 27 May 2020

Submitted as: research article | 27 May 2020

Review status
This preprint is currently under review for the journal ACP.

Determination of the absorption cross-sections of higher order iodine oxides at 355 nm and 532 nm

Thomas R. Lewis1,2, Juan Carlos Gómez Martin3, Mark A. Blitz2, Carlos A. Cuevas1, John M. C. Plane2, and Alfonso Saiz-Lopez1 Thomas R. Lewis et al.
  • 1Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, Spain
  • 2School of Chemistry, University of Leeds, LS29JT, Leeds, UK
  • 3Instituto de Astrofísica de Andalucía, CSIC, 18008, Granada, Spain

Abstract. Iodine oxides (IxOy) play an important role in the atmospheric chemistry of iodine. They are initiators of new particle formation events in the coastal and polar boundary layer and act as iodine reservoirs in tropospheric ozone-depleting chemical cycles. Despite the importance of the aforementioned processes, the photochemistry of these molecules has not been studied in detail previously. Here, we report the first determination of the absorption cross sections of IxOy, x = 2, 3, 5, y = 1–12 at λ = 355 nm by combining pulsed laser photolysis of I2/O3 gas mixtures in air with time-resolved photo-ionization time-of-flight mass spectrometry, using NO2 actinometry for signal calibration. The oxides selected for absorption cross section determinations are those presenting the strongest signals in the mass spectra, where signals containing 4 iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355 nm, IO = (1.2 ± 0.1) ×  10–18 cm2, which is found to be in good agreement with the most recent literature. The results obtained are: σ355 nm, I2O3 < 5 × 10–19 cm2 molecule−1, σ355 nm, I2O4 = (3.9 ± 1.2) × 10–18 cm2 molecule−1, σ355 nm, I3O6 = (6.1 ± 1.6) × 10–18 cm2 molecule−1, σ355 nm, I3O7 = (5.3 ± 1.4) × 10–18 cm2 molecule−1 and, σ355 nm, I5O12 = (9.8 ± 1.0) × 10–18 cm2 molecule1. Photodepletion at λ = 532 nm was only observed for OIO, which enabled determining upper limits for the absorption cross sections of IxOy at 532 nm using OIO as an actinometer. These measurements are supplemented with ab-initio calculations of electronic spectra in order to estimate atmospheric photolysis rates J(IxOy). Our results confirm a high J(IxOy) scenario where IxOy is efficiently removed at daytime, implying enhanced iodine-driven ozone depletion and hindering iodine particle formation. Possible I2O3 and I2O4 photolysis products are discussed, including IO3, which may be a precursor to iodic acid (HIO3) in the presence of HO2.

Thomas R. Lewis et al.

Interactive discussion

Status: open (until 22 Jul 2020)
Status: open (until 22 Jul 2020)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Thomas R. Lewis et al.

Thomas R. Lewis et al.

Viewed

Total article views: 293 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
229 63 1 293 11 7
  • HTML: 229
  • PDF: 63
  • XML: 1
  • Total: 293
  • BibTeX: 11
  • EndNote: 7
Views and downloads (calculated since 27 May 2020)
Cumulative views and downloads (calculated since 27 May 2020)

Viewed (geographical distribution)

Total article views: 252 (including HTML, PDF, and XML) Thereof 252 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 05 Jul 2020
Publications Copernicus
Download
Short summary
Iodine-bearing gasses emitted from the sea surface are chemically processed in the atmosphere, leading to iodine accumulation in aerosol and transport to continental ecosystems. Such processing involves light-induced break-up of large, particle-forming iodine oxides, into of smaller, ozone-depleting molecules. We combine experiments and theory to report the photolysis efficiency of iodine oxides, required to assess the impact of iodine on ozone depletion and particle formation.
Iodine-bearing gasses emitted from the sea surface are chemically processed in the atmosphere,...
Citation