| Autor: |
Gómez Martín JC; Instituto de Astrofísica de Andalucía, CSIC, Granada 18008, Spain., Lewis TR; Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, Madrid 28006, Spain.; School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K., James AD; School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K., Saiz-Lopez A; Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, Madrid 28006, Spain., Plane JMC; School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2022 Jun 01; Vol. 144 (21), pp. 9240-9253. Date of Electronic Publication: 2022 May 23. |
| DOI: |
10.1021/jacs.1c12957 |
| Abstrakt: |
Iodine chemistry is an important driver of new particle formation in the marine and polar boundary layers. There are, however, conflicting views about how iodine gas-to-particle conversion proceeds. Laboratory studies indicate that the photooxidation of iodine produces iodine oxides (I x O y ), which are well-known particle precursors. By contrast, nitrate anion chemical ionization mass spectrometry (CIMS) observations in field and environmental chamber studies have been interpreted as evidence of a dominant role of iodic acid (HIO 3 ) in iodine-driven particle formation. Here, we report flow tube laboratory experiments that solve these discrepancies by showing that both I x O y and HIO 3 are involved in atmospheric new particle formation. I 2 O y molecules ( y = 2, 3, and 4) react with nitrate core ions to generate mass spectra similar to those obtained by CIMS, including the iodate anion. Iodine pentoxide (I 2 O 5 ) produced by photolysis of higher-order I x O y is hydrolyzed, likely by the water dimer, to yield HIO 3 , which also contributes to the iodate anion signal. We estimate that ∼50% of the iodate anion signals observed by nitrate CIMS under atmospheric water vapor concentrations originate from I 2 O y . Under such conditions, iodine-containing clusters and particles are formed by aggregation of I 2 O y and HIO 3 , while under dry laboratory conditions, particle formation is driven exclusively by I 2 O y . An updated mechanism for iodine gas-to-particle conversion is provided. Furthermore, we propose that a key iodine reservoir species such as iodine nitrate, which we observe as a product of the reaction between iodine oxides and the nitrate anion, can also be detected by CIMS in the atmosphere. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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