On the mechanism of iodine oxide particle formation

Martı́n, Juan Carlos Gómez; Gálvez, Óscar; Baeza‐Romero, M. T.; Ingham, T.; Plane, J. M. C.; Blitz, Mark A.

doi:10.1039/c3cp51217g

Cited by 61 publications

(89 citation statements)

References 53 publications

(84 reference statements)

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“…Prominent featureless absorption bands of I x O y species have been experimentally observed in the UV region (Bloss et al, 2001;Gómez Martín et al, 2005;. The photolysis thresholds of the iodine oxides are mostly in the near-infrared region (Gálvez et al, 2013).…”

Section: Absorption Cross-sections Of I X O Ymentioning

confidence: 93%

“…Based on the kinetic behaviour of the absorption spectra observed in the laboratory, tentative spectral assignments and estimation of the corresponding absorption cross-section have been reported. While Bloss et al (2001) assigned the broadband absorption appearing under the IO spectrum to a single species (I 2 O 2 ), Gómez Martín et al ( , 2007 obtained evidence of the same band resulting from an overlap of at least two different iodine oxides (I 2 O 2 and I 2 O 3 ). Here, in order to calculate atmospheric photolysis rates, we adopt for these two species the spectra extracted and scaled to absolute absorption cross-section by Gómez Martín et al (2005) (Fig.…”

Section: Absorption Cross-sections Of I X O Ymentioning

confidence: 99%

“…Table 1 presents the bimolecular, thermal decomposition and termolecular reactions of iodine species included in the chemical mechanism. Updates with respect to previous analyses Saiz-Lopez et al, 2012b) are mainly based on theoretical studies on the formation, photochemistry and thermal decomposition of higher iodine oxides, collectively called I x O y (Gómez Martín et al, 2007;Kaltsoyannis and Plane, 2008;Gómez Martín and Plane, 2009). A distinct feature of iodine chemistry, with respect to the other halogens, is the formation of I x O y (where usually x = 2 and y = 2, 3, or 4) from recombination reactions of IO with itself (y = 2) and with OIO (y = 3), or OIO with itself (y = 4).…”

Section: Atmospheric Chemistry Of Iodinementioning

confidence: 99%

“…Saiz-Lopez et al: Iodine chemistry in the troposphere and its effect on ozone ments over the open ocean environment Mahajan et al, 2010Mahajan et al, , 2012Gómez Martín et al, 2013b;Großmann et al, 2013;Lawler et al, 2014). Early pioneering work by Chameides and Davis (1980) and Solomon et al (1994) showed that both organic and inorganic iodine compounds photo-dissociate rapidly in the troposphere to release iodine atoms, which then react mainly with ozone to generate IO.…”

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Iodine chemistry in the troposphere and its effect on ozone

et al. 2014

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Abstract. Despite the potential influence of iodine chemistry on the oxidizing capacity of the troposphere, reactive iodine distributions and their impact on tropospheric ozone remain almost unexplored aspects of the global atmosphere. Here we present a comprehensive global modelling experiment aimed at estimating lower and upper limits of the inorganic iodine burden and its impact on tropospheric ozone. Two sets of simulations without and with the photolysis of I x O y oxides (i.e. I 2 O 2 , I 2 O 3 and I 2 O 4 ) were conducted to define the range of inorganic iodine loading, partitioning and impact in the troposphere. Our results show that the most abundant daytime iodine species throughout the middle to upper troposphere is atomic iodine, with an annual average tropical abundance of (0.15-0.55) pptv. We propose the existence of a "tropical ring of atomic iodine" that peaks in the tropical upper troposphere (∼11-14 km) at the equator and extends to the sub-tropics (30 • N-30 • S). Annual average daytime I / IO ratios larger than 3 are modelled within the tropics, reaching ratios up to ∼20 during vigorous uplift events within strong convective regions. We calculate that the integrated contribution of catalytic iodine reactions to the total rate of tropospheric ozone loss (IO x Loss ) is 2-5 times larger than the combined bromine and chlorine cycles. When I x O y photolysis is included, IO x Loss represents an upper limit of approximately 27, 14 and 27 % of the tropical annual ozone loss for the marine boundary layer (MBL), free troposphere (FT) and upper troposphere (UT), respectively, while the lower limit throughout the tropical troposphere is ∼9 %. Our results indicate that iodine is the second strongest ozone-depleting family throughout the global marine UT and in the tropical MBL.We suggest that (i) iodine sources and its chemistry need to be included in global tropospheric chemistry models, (ii) experimental programs designed to quantify the iodine budget in the troposphere should include a strategy for the measurement of atomic I, and (iii) laboratory programs are needed to characterize the photochemistry of higher iodine oxides to determine their atmospheric fate since they can potentially dominate halogen-catalysed ozone destruction in the troposphere.

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Section: Absorption Cross-sections Of I X O Ymentioning

confidence: 93%

Section: Absorption Cross-sections Of I X O Ymentioning

confidence: 99%

Section: Atmospheric Chemistry Of Iodinementioning

confidence: 99%

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Iodine chemistry in the troposphere and its effect on ozone

et al. 2014

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“…O 3 can directly react with volatile organic compounds or indirectly affect sulfuric acid formation via hydroxyl and hydroperoxy radicals (Berndt et al, 2010;Gómez Martín et al, 2013;Sorribas et al, 2015;Guo et al, 2012), and thus O 3 in the atmosphere may theoretically play a role in NPF. Previous research showed that elevated O 3 concentration was beneficial to the occurrence of NPF events Guo et al, 2012;Zhang et al, 2016;Huang et al, 2016), and our results did not directly show a similar phenomenon.…”

Section: Condensation Sinks and Sources Of Npfmentioning

confidence: 99%

Investigation of new particle formation at the summit of Mt. Tai, China

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Sui²,

Chen³

et al. 2018

Atmos. Chem. Phys.

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Abstract. To date, few comprehensive field observations of new particle formation (NPF) have been carried out at mountaintop sites in China. In this study, simultaneous measurements of particle size distribution, trace gases, meteorological parameters, and mass concentration and chemical composition of PM 2.5 were performed at the summit of Mt. Tai (1534 m a.s.l.) from 25 July to 24 August 2014 (Phase I), 21 September to 9 December 2014 (Phase II), and 16 June to 7 August 2015 (Phase III) to investigate characteristics and favorable conditions of NPF in a relatively clean mountaintop environment. The NPF events were identified based on particle size distribution measured by the neutral cluster and air ion spectrometer (NAIS), and 66 such events were observed during a period of 164 days -corresponding to an occurrence frequency of 40 %. The formation rates of 3 nm particles (J 3 ) and growth rates were in the ranges of 0.82-25.04 cm −3 s −1 and 0.58-7.76 nm h −1 , respectively. On average, the condensation sink (CS), O 3 concentration, air temperature, and relative humidity were lower, whereas the SO 2 concentration was higher on NPF days than that on non-NPF days. The CS on Mt. Tai was at a low level and lower CS was critical for NPF. NPF events were common when wind came from the east-southeast and west-southwest, which was probably associated with relatively lower CS in the east-southeast and higher SO 2 concentration in the west-southwest. O 3 was not a governing factor for NPF in this study, and a high level of NO x concentration might be responsible for the decreased O 3 concentration on NPF days. Three categories of backward trajectories were classified, among which the continental air mass was the majority. The continental air mass passing through more polluted areas (denoted as Type I) favored NPF because of enhanced SO 2 concentration and potential ammonia with it. An in-depth analysis of SO 2 indicated that sulfuric acid was a dominant precursor on Mt. Tai; meanwhile, biogenic organics released from ambient forests in warm seasons and anthropogenic volatile organic compounds emitted from domestic heating in cold seasons also promoted NPF.

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Threshold Photoelectron Spectroscopy of IO and HOI

et al. 2019

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Iodine oxides appear as reactive intermediates in atmospheric chemistry. Here, we investigate IO and HOI by mass-selective threshold photoelectron spectroscopy (ms-TPES), using synchrotron radiation. IO and HOI are generated by photolyzing iodine in the presence of ozone. For both molecules, accurate ionization energies are determined, 9.71 � 0.02 eV for IO and 9.79 � 0.02 eV for HOI. The strong spin-spin interaction in the 3 Σ À ground state of IO + leads to an energy splitting into the Ω = 0 and Ω = � 1 sublevels. Upon ionization, the IÀ O bond shortens significantly in both molecules; thus, a vibrational progression, assigned to the IÀ O stretch, is apparent in both spectra.

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On the mechanism of iodine oxide particle formation

Cited by 61 publications

References 53 publications

Iodine chemistry in the troposphere and its effect on ozone

Iodine chemistry in the troposphere and its effect on ozone

Investigation of new particle formation at the summit of Mt. Tai, China

Threshold Photoelectron Spectroscopy of IO and HOI

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