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DOI	10.5194/acp-20-10865-2020
	Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm
	Lewis T.R.; Martín J.C.G.; Blitz M.A.; Cuevas C.A.; Plane J.M.C.; Saiz-Lopez A.
发表日期	2020
ISSN	1680-7316
起始页码	10865
结束页码	10887
卷号	20 期号:18
英文摘要	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 layers 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 D 2, 3, 5, y D 1 12 at λ D 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 four iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355 nm; IO D (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; I2/O3 <5 × 10-19 cm2 molec.-1, σ355 nm; I2O4 D (3.9 ± 1.2/ × 10-18 cm2 molec.-1, σ355 nm; I3O6 D (6.1 ± 1.6/ × 10-18 cm2 molec.-1, σ355 nm; I3O7 D (5.3 ± 1.4/ × 10-18 cm2 molec.-1, and σ355 nm; I5O12 D (9.8 ± 1.0/ × 10-18 cm2 molec.-1. Photodepletion at λ D 532 nm was only observed for OIO, which enabled determination of 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 during 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. © 2020 Author(s).
语种	英语
scopus关键词	absorption; aerosol formation; iodine; mass spectrometry; ozone depletion; photochemistry; photolysis; signal processing
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/247518
作者单位	Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, Spain; School of Chemistry, University of Leeds, Leeds, LS29JT, United Kingdom; Instituto de Astrofísica de Andaluciá, CSIC, Granada, 18008, Spain
推荐引用方式 GB/T 7714	Lewis T.R.,Martín J.C.G.,Blitz M.A.,et al. Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm[J],2020,20(18).
APA	Lewis T.R.,Martín J.C.G.,Blitz M.A.,Cuevas C.A.,Plane J.M.C.,&Saiz-Lopez A..(2020).Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(18).
MLA	Lewis T.R.,et al."Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.18(2020).