Direct Kinetic Measurements of Criegee Intermediate (CH
 2
 OO) Formed by Reaction of CH
 2
 I with O
 2

Welz, Oliver; Savee, John David; Osborn, David L.; Vasu, Subith; Percival, Carl J.; Shallcross, Dudley E.; Taatjes, Craig A.

doi:10.1126/science.1213229

Cited by 662 publications

(799 citation statements)

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“…A series of more recent laboratory and theoretical studies also presented a wide range of recommendations for the reaction rates of R 5 . Welz et al 12,44 reported a significantly higher upper limit for k R5 (k R5a+R5b = 4 × 10 −15 molecules cm 3 s −1 ) compared to the 9 × 10 −17 molecules cm 3 s −1 from Stone et al 13 Stone et al 13 also experimentally derived k R5a (5.4 × 10 −17 molecules cm 3 s −1 ), very close to that applied in MCM 3.2. Theoretical studies 45,46 evaluating the kinetics of sCI with water dimer argue that a reaction with water dimer becomes the dominant sCI chemical sink especially for the small sCI.…”

Section: ■ Results and Discussionmentioning

confidence: 54%

“…Therefore, if we include the fast water dimer reaction in the zero-dimensional model calculation, it results in no contribution to H 2 SO 4 formation from R4. For comparison purpose, we calculated CH 2 OO with the upper limit of k R5 presented by Welz et al 12 The results shown in Figure 3c suggest significant suppression in CH 2 OO by applying the fast k R5 , which would cause substantially less contribution of the sCI reaction channel to H 2 SO 4 formation. Further studies on chemical interactions between water vapor and sCIs are urged in this context.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

Kim

Lefer

Flynn

et al. 2015

Environ. Sci. Technol.

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We present field observations made in June 2011 downwind of Dallas−Fort Worth, TX, and evaluate the role of stabilized Criegee radicals (sCIs) in gaseous sulfuric acid (H 2 SO 4 ) production. Zerodimensional model calculations show that sCI from biogenic volatile organic compounds composed the majority of the sCIs. The main uncertainty associated with an evaluation of H 2 SO 4 production from the sCI reaction channel is the lack of experimentally determined reaction rates for sCIs formed from isoprene ozonolysis with SO 2 along with systematic discrepancies in experimentally derived reaction rates between other sCIs and SO 2 and water vapor. In general, the maximum of H 2 SO 4 production from the sCI channel is found in the late afternoon as ozone increases toward the late afternoon. The sCI channel, however, contributes minor H 2 SO 4 production compared with the conventional OH channel in the mid-day. Finally, the production and the loss rates of H 2 SO 4 are compared. The application of the recommended mass accommodation coefficient causes significant overestimation of H 2 SO 4 loss rates compared with H 2 SO 4 production rates. However, the application of a lower experimental value for the mass accommodation coefficient provides good agreement between the loss and production rates of H 2 SO 4 . The results suggest that the recommended coefficient for the H 2 O surface may not be suitable for this relatively dry environment. ■ INTRODUCTIONMost sulfur compounds emitted to the atmosphere are in a reduced form (e.g., sulfur dioxide, SO 2 (IV)). Atmospheric gasphase oxidation processes sulfur throughout the troposphere and the stratosphere and transforms these emitted sulfur compounds into the most oxidized form of gas-phase sulfuric acid (H 2 SO 4 ), unless heterogeneous uptake transforms the sulfur into condensed-phase forms. The discussion in this paper will focus exclusively on gas-phase H 2 SO 4 formation from gas-phase SO 2 oxidation. Although sulfur compounds contribute a relatively minor fraction of the chemical composition of the troposphere, 1 the critical role of H 2 SO 4 in determining acidity in precipitation 2 and forming particles that influence regional and global climate has been highlighted. 3−5 Anthropogenic sulfur emission in the form of SO 2 is currently estimated to dominate global sulfur emissions, followed by oceanic dimethylsulfide (CH 3 SCH 3 ). 6 The gas-phase atmospheric oxidation processes of SO 2 were thought previously to be driven mostly by hydroxyl radical (OH), as shown in R1−R3. 7The potential role of stabilized Criegee biradicals (sCIs) 8 in SO 2 oxidation has been discussed since the 1970s. Cox and Penkett 9 reported significant SO 3 formation rates from chamber experiments with various alkene compounds, ozone (O 3 ), and SO 2 . They speculated sCIs prompted SO 2 oxidation because the reaction between SO 2 and O 3 is insignificant under atmospheric conditions. Calvert and Stockwell 2 presented comprehensive zero-dimensional model calculation results examining atmosp...

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Section: ■ Results and Discussionmentioning

confidence: 54%

Section: ■ Results and Discussionmentioning

confidence: 99%

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

Kim

Lefer

Flynn

et al. 2015

Environ. Sci. Technol.

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“…4,13 Welz et al 4 reported an efficient way to prepare Criegee intermediates. For example, CH 2 OO can be prepared via (R6) + (R7a).…”

Section: O( 1 D) + H 2 O -2oh (R5)mentioning

confidence: 99%

“…Now it is generally accepted that ozonolysis of alkenes proceeds via Criegee intermediates, highly reactive species postulated in 1949 by Rudolf Criegee. 1,2 In the troposphere, Criegee intermediates are involved in several important atmospheric reactions, 3 including reactions with SO 2 and NO 2 , [4][5][6][7] or can be photolyzed by near UV light, [7][8][9][10] as shown for CH 2 The formation of SO 3 and NO 3 , as in (R2) and (R3), plays an important role in atmospheric chemistry, 11,12 including aerosol and cloud formation. The formation of O( 1 D), as in (R4), will result in OH formation through (R5).…”

mentioning

confidence: 99%

The UV absorption spectrum of the simplest Criegee intermediate CH₂OO

Ting

Chen

Chao

et al. 2014

Phys. Chem. Chem. Phys.

129

224

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SO 2 scavenging and self-reaction of CH 2 OO were utilized for the decay of CH 2 OO to extract the absorption spectrum of CH 2 OO under bulk conditions. Absolute absorption cross sections of CH 2 OO at 308.4 and 351.8 nm were obtained from laser-depletion measurements in a jet-cooled molecular beam. The peak cross section is (1.23 AE 0.18) Â 10 À17 cm 2 at 340 nm.Ozonolysis is a major removal mechanism in the troposphere for unsaturated hydrocarbons which are emitted in large quantities from both natural and human sources. Now it is generally accepted that ozonolysis of alkenes proceeds via Criegee intermediates, highly reactive species postulated in 1949 by Rudolf Criegee. 1,2 In the troposphere, Criegee intermediates are involved in several important atmospheric reactions, 3 including reactions with SO 2 and NO 2 , 4-7 or can be photolyzed by near UV light, 7-10 as shown for CH 2 OO in (R1)-(R4).The formation of SO 3 and NO 3 , as in (R2) and (R3), plays an important role in atmospheric chemistry, 11,12 including aerosol and cloud formation. The formation of O( 1 D), as in (R4), will result in OH formation through (R5).Because CH 2 OO absorbs strongly at wavelengths longer than 300 nm, 7-9 tropospheric photolysis of CH 2 OO would be quite efficient with an effective photolysis lifetime on the order of 1 second. 8 As a result, the OH formation of (R4) + (R5) may contribute significantly to the atmospheric OH concentrations.Despite their importance, the direct detection of Criegee intermediates was not realized until recently. 4,13 Welz et al. 4 reported an efficient way to prepare Criegee intermediates. For example, CH 2 OO can be prepared via (R6) + (R7a). Welz et al. 4 also demonstrated the direct detection of CH 2 OO by using vacuum UV photoionization mass spectrometry. The parent ion CH 2 O 2 + was observed when the photon energy exceeded the ionization energy of CH 2 OO (10.0 eV); other isomers like dioxirane and formic acid were excluded due to their different ionization energies. 4 At low pressure, the yield of (R7a) is close to unity, 14,15 while the adduct formation (R7b) may dominate at near atmospheric pressures. 14The kinetics of CH 2 OO reactions with SO 2 and NO 2 were investigated by Welz et al. 4 and by Stone et al. 5 by observing the disappearance of CH 2 OO and by detecting the H 2 CO products, respectively. The rate coefficients of these reactions were found to be unexpectedly rapid and imply a substantially greater role of Criegee intermediates in models of tropospheric sulfate and nitrate chemistry.Beames et al. 8 recorded the UV spectrum of CH 2 OO through observing its depletion in a molecular beam upon laser irradiation (an action spectrum). Based on their laser pulse energy and spot size, Beames et al. 8 roughly estimated the peak absorption cross section to be 5 Â 10 À17 cm 2 (at 335 nm with FWHM B40 nm). Lehman et al. 10 measured the angular and velocity distributions of the O( 1 D) photoproduct arising from UV excitation of CH 2 OO in the 300-365 nm range. From the observed

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“…15−28 A key reaction in atmospheric chemistry is that of water with the stabilized Criegee intermediate. [18][19][20][21][22][23][25][26][27]29,30 It is known that this reaction leads to the formation of hydroxyalkyl hydroperoxide, carboxylic acids, carbonyl compounds, and H 2 O 2 , 4,6,31−33 species with important environmental implications. In particular, H 2 O 2 is a molecule of broad tropospheric and biological relevance.…”

Section: Introductionmentioning

confidence: 99%

Role of Tunable Acid Catalysis in Decomposition of α-Hydroxyalkyl Hydroperoxides and Mechanistic Implications for Tropospheric Chemistry

et al. 2014

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Electronic structure calculations have been used to investigate possible gasphase decomposition pathways of α-hydroxyalkyl hydroperoxides (HHPs), an important source of tropospheric hydrogen peroxide and carbonyl compounds. The uncatalyzed as well as waterand acid-catalyzed decomposition of multiple HHPs have been examined at the M06-2X/augcc-pVTZ level of theory. The calculations indicate that, compared to an uncatalyzed or watercatalyzed reaction, the free-energy barrier of an acid-catalyzed decomposition leading to an aldehyde or ketone and hydrogen peroxide is dramatically lowered. The calculations also find a direct correlation between the catalytic effect of an acid and the distance separating its hydrogen acceptor and donor sites. Interestingly, the catalytic effect of an acid on the HHP decomposition resulting in the formation of carboxylic acid and water is relatively much smaller. Moreover, since the free-energy barrier of the acid-catalyzed aldehyde-or ketoneforming decomposition is ∼25% lower than that required to break the O−OH linkage of the HHP leading to the formation of hydroxyl radical, these results suggest that HHP decomposition is likely not an important source of tropospheric hydroxyl radical. Finally, transition state theory estimates indicate that the effective rate constants for the acid-catalyzed aldehyde-or ketone-forming HHP decomposition pathways are 2− 3 orders of magnitude faster than those for the water-catalyzed reaction, indicating that an acid-catalyzed HHP decomposition is kinetically favored as well.

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Direct Kinetic Measurements of Criegee Intermediate (CH ₂ OO) Formed by Reaction of CH ₂ I with O ₂

Cited by 662 publications

References 50 publications

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

The UV absorption spectrum of the simplest Criegee intermediate CH₂OO

Role of Tunable Acid Catalysis in Decomposition of α-Hydroxyalkyl Hydroperoxides and Mechanistic Implications for Tropospheric Chemistry

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Direct Kinetic Measurements of Criegee Intermediate (CH 2 OO) Formed by Reaction of CH 2 I with O 2

Cited by 662 publications

References 50 publications

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

The UV absorption spectrum of the simplest Criegee intermediate CH2OO

Role of Tunable Acid Catalysis in Decomposition of α-Hydroxyalkyl Hydroperoxides and Mechanistic Implications for Tropospheric Chemistry

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Resources

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Direct Kinetic Measurements of Criegee Intermediate (CH ₂ OO) Formed by Reaction of CH ₂ I with O ₂

The UV absorption spectrum of the simplest Criegee intermediate CH₂OO