Raman spectra of I4O9 formed by the reaction of iodine with ozone

Sunder, S.; Wren, J. C.; Vikis, A.C.

doi:10.1002/jrs.1250160611

Cited by 15 publications

(7 citation statements)

References 10 publications

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“…If iodine oxyacids are present in the particles, their origin cannot be explained by the known gas‐phase chemistry. Sunder and Vikis [1987] identified the solid product formed by the dark reaction of I 2 with O 3 under saturated water vapor conditions as HIO 3 ; however, this reaction had yielded only I 4 O 9 when conducted under completely dry conditions [ Sunder et al , 1985]. The detailed gas‐phase chemical mechanism is not known in either case, but is thought to involve the direct reaction of I 2 and O 3 to form a cyclic transition state that decomposes into either IO, I, and O 2 , or IO 2 and IO, the latter path being nonnegligible [ Vikis and MacFarlane , 1985].…”

Section: Integrated Interpretation Of the Aerosol Chemistrymentioning

confidence: 99%

New particle formation from photooxidation of diiodomethane (CH₂I₂)

Jiménez¹

2003

J. Geophys. Res.

238

266

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[1] Photolysis of CH 2 I 2 in the presence of O 3 has been proposed as a mechanism leading to intense new particle formation in coastal areas. We report here a comprehensive laboratory chamber study of this system. Rapid homogeneous nucleation was observed over three orders of magnitude in CH 2 I 2 mixing ratio, down to a level of 15 ppt ($4 Â 10 8 molec. cm À3 ) comparable to the directly measured total gas-phase iodine species concentrations in coastal areas. After the nucleation burst, the observed aerosol dynamics in the chamber was dominated by condensation of additional vapors onto existing particles and particle coagulation. Particles formed under dry conditions are fractal agglomerates with mass fractal dimension, D f $ 1.8-2.5. Higher relative humidity (65%) does not change the nucleation or growth behavior from that under dry conditions, but results in more compact and dense particles (D f $ 2.7). On the basis of the known gas-phase chemistry, OIO is the most likely gas-phase species to produce the observed nucleation and aerosol growth; however, the current understanding of this chemistry is very likely incomplete. Chemical analysis of the aerosol using an Aerodyne Aerosol Mass Spectrometer reveals that the particles are composed mainly of iodine oxides but also contain water and/or iodine oxyacids. The system studied here can produce nucleation events as intense as those observed in coastal areas. On the basis of comparison between the particle composition, hygroscopicity, and nucleation and growth rates observed in coastal nucleation and in the experiments reported here, it is likely that photooxidation of CH 2 I 2 , probably aided by other organic iodine compounds, is the mechanism leading to the observed new particle formation in the west coast of Ireland.

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Section: Integrated Interpretation Of the Aerosol Chemistrymentioning

confidence: 99%

New particle formation from photooxidation of diiodomethane (CH₂I₂)

Jiménez¹

2003

J. Geophys. Res.

238

266

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“…Reducing the iodine and ozone concentration towards ambient levels, particle production in the dark became undetectable. Vikis and MacFarlane (1985), Sunder et al (1985) and Sunder and Vikis (1987) made studies of the reaction rate and products in the I 2 + O 3 reaction under light and dark conditions. The products were not tracked in the current study, but the concentration of reactants are comparable to those used in the Vikis and MacFarlane (1985) study (I 2 from 1 to 10×10 14 and O 3 of 1 to 100×10 14 molec.…”

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confidence: 99%

Direct evidence for coastal iodine particles from Laminaria macroalgae – linkage to emissions of molecular iodine

et al. 2004

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Abstract.Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH 2

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“…There are many iodine oxide compounds (e.g., HIO 3 , HI 3 O 8 , I 2 O 5 , I 4 O 9 ) but the one most commonly studied for reaction with aluminum (Al) is diiodide pentoxide, I 2 O 5 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . There are reasons for favoring I 2 O 5 for combustion with Al: (1) I 2 O 5 has an oxidation state of five which makes it a strong oxidizer for combustion applications; (2) I 2 O 5 is semi-stable, depending on atmospheric conditions, and easily handled in powder form; and (3) I 2 O 5 is relatively easy to produce and readily available.…”

Section: Introductionmentioning

confidence: 99%