scholarly journals Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2

2015 ◽  
Vol 112 (35) ◽  
pp. 10857-10862 ◽  
Author(s):  
Hao-Li Huang ◽  
Wen Chao ◽  
Jim Jr-Min Lin
Keyword(s):  
Water Vapor ◽  
Atmospheric Chemistry ◽  
High Water ◽  
Water Dimer ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Criegee Intermediates ◽  
Reaction With Water ◽  
The Impact ◽  
Kinetics Of

Criegee intermediates are thought to play a role in atmospheric chemistry, in particular, the oxidation of SO2, which produces SO3 and subsequently H2SO4, an important constituent of aerosols and acid rain. However, the impact of such oxidation reactions is affected by the reactions of Criegee intermediates with water vapor, because of high water concentrations in the troposphere. In this work, the kinetics of the reactions of dimethyl substituted Criegee intermediate (CH3)2COO with water vapor and with SO2 were directly measured via UV absorption of (CH3)2COO under near-atmospheric conditions. The results indicate that (i) the water reaction with (CH3)2COO is not fast enough (kH2O < 1.5 × 10−16 cm3s−1) to consume atmospheric (CH3)2COO significantly and (ii) (CH3)2COO reacts with SO2 at a near–gas-kinetic-limit rate (kSO2 = 1.3 × 10−10 cm3s−1). These observations imply a significant fraction of atmospheric (CH3)2COO may survive under humid conditions and react with SO2, very different from the case of the simplest Criegee intermediate CH2OO, in which the reaction with water dimer predominates in the CH2OO decay under typical tropospheric conditions. In addition, a significant pressure dependence was observed for the reaction of (CH3)2COO with SO2, suggesting the use of low pressure rate may underestimate the impact of this reaction. This work demonstrates that the reactivity of a Criegee intermediate toward water vapor strongly depends on its structure, which will influence the main decay pathways and steady-state concentrations for various Criegee intermediates in the atmosphere.

Structure-dependent reactivity of Criegee intermediates studied with spectroscopic methods

2017 ◽  
Vol 46 (24) ◽  
pp. 7483-7497 ◽  
Author(s):  
Jim Jr-Min Lin ◽  
Wen Chao
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Atom ◽  
Atmospheric Chemistry ◽  
Spectroscopic Method ◽  
Water Dimer ◽  
Spectroscopic Methods ◽  
Criegee Intermediates ◽  
Pros And Cons ◽  
Intramolecular Hydrogen

Criegee intermediates can be prepared by two methods and may play important roles in atmospheric chemistry. Anti-type Criegee intermediates react quickly with water dimer; Syn-type Criegee intermediates may undergo thermal decomposition via intramolecular hydrogen atom tunneling. In addition, the pros and cons of each spectroscopic method in probing Criegee intermediates in kinetic experiments will also be discussed.

scholarly journals Kinetics of dimethyl sulfide (DMS) reactions with isoprene-derived Criegee intermediates studied with direct UV absorption

2020 ◽  
Author(s):  
Mei-Tsan Kuo ◽  
Isabelle Weber ◽  
Christa Fittschen ◽  
Jim Jr-Min Lin
Keyword(s):  
Atmospheric Chemistry ◽  
Dimethyl Sulfide ◽  
Relative Rate ◽  
Chem Phys ◽  
High Reactivity ◽  
Rate Coefficients ◽  
Visible Absorption ◽  
Criegee Intermediates ◽  
The Individual ◽  
Kinetics Of

Abstract. Criegee intermediates (CIs) are formed in the ozonolysis of unsaturated hydrocarbons and play a role in atmospheric chemistry as a non-photolytic OH source or a strong oxidant. Using a relative rate method in an ozonolysis experiment, Newland et al. [Atmos. Chem. Phys., 15, 9521–9536, 2015] reported high reactivity of isoprene-derived Criegee intermediates towards dimethyl sulfide (DMS) relative to that towards SO2 with the ratio of the rate coefficients kDMS+CI / kSO2+CI = 3.5 ± 1.8. Here we reinvestigated the kinetics of DMS reactions with two major Criegee intermediates formed in isoprene ozonolysis, CH2OO and methyl vinyl ketone oxide (MVKO). The individual CI was prepared following reported photolytic method with suitable (diiodo) precursors in the presence of O2. The concentration of CH2OO or MVKO was monitored directly in real time through their intense UV-visible absorption. Our results indicate the reactions of DMS with CH2OO and MVKO are both very slow; the upper limits of the rate coefficients are 4 orders of magnitude smaller than that reported by Newland et al. These results suggest that the ozonolysis experiment could be complicated such that interpretation should be careful and these CIs would not oxidize atmospheric DMS at any substantial level.

Mechanisms for ozone-initiated removal of biomass burning products from the atmosphere

2018 ◽  
Vol 15 (2) ◽  
pp. 83 ◽  
Author(s):  
Jianfei Sun ◽  
Qiong Mei ◽  
Bo Wei ◽  
Long Huan ◽  
Ju Xie ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Rate Constants ◽  
Computational Method ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Positive Dependence ◽  
Elementary Reactions ◽  
Criegee Intermediates ◽  
Ozone Addition ◽  
Kinetics Of

Environmental contextAn important product of biomass burning is catechol: its presence in the atmosphere can have adverse effects on health, and can lead to the formation of secondary organic aerosols. We report a theoretical study on the mechanisms and kinetics of removal of catechol from the atmosphere by reaction with ozone. These data will provide insight into the ozonolysis of other lignin compounds produced by biomass burning. AbstractWe examined the ozone-initiated oxidation of catechol, an intermediate of lignin pyrolysis in the atmosphere, by using the theoretical computational method at the M06-2X/aug-cc-pVDZ//M06-2X/6-31+G(d,p) level. Six ozone-addition channels of the initial reactions and the further reactions of the Criegee intermediates are proposed. The complete degradation processes of the Criegee intermediates in the presence of NO and H2O were elucidated. The predicted reaction products for the ozonolysis of catechol, such as malealdehyde (P10), oxalic acid (P11) and CO2, were detected experimentally in the gas-phase. Moreover, the microcanonical rate constants of the crucial elementary reactions were determined by the Rice–Ramsperger–Kassel–Marcus theory. The total rate constant for the ozonolysis of catechol under atmospheric conditions is 1.37 × 10−18 cm3 molecule−1 s−1, which compares favourably to the experimentally determined values. The bimolecular rate constants showed positive dependence on temperature and negative dependence on pressure. The atmospheric lifetime of catechol with respect to ozone was estimated to be 12.07 days. We also found that the ozonolysis of catechol is more likely to occur in aqueous solution. The present work has provided a comprehensive investigation of the ozonolysis of catechol. The methods we used can serve as a model for analysing the ozonolysis of other lignin compounds.

scholarly journals A Global MODIS Water Vapor Database for the Operational Atmospheric Correction of Historic and Recent Landsat Imagery

2019 ◽  
Vol 11 (3) ◽  
pp. 257 ◽  
Author(s):  
David Frantz ◽  
Marion Stellmes ◽  
Patrick Hostert
Keyword(s):  
Water Vapor ◽  
Landsat Imagery ◽  
Atmospheric Correction ◽  
Atmospheric Conditions ◽  
Wet Season ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Daily Water ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact

Analysis Ready Data (ARD) have undergone the most relevant pre-processing steps to satisfy most user demands. The freely available software FORCE (Framework for Operational Radiometric Correction for Environmental monitoring) is capable of generating Landsat ARD. An essential step of generating ARD is atmospheric correction, which requires water vapor data. FORCE relies on a water vapor database obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). However, two major drawbacks arise from this strategy: (1) The database has to be compiled for each study area prior to generating ARD; and (2) MODIS and Landsat commissioning dates are not well aligned. We have therefore compiled an application-ready global water vapor database to significantly increase the operational readiness of ARD production. The free dataset comprises daily water vapor data for February 2000 to July 2018 as well as a monthly climatology that is used if no daily value is available. We systematically assessed the impact of using this climatology on surface reflectance outputs. A global random sample of Landsat 5/7/8 imagery was processed twice (i) using daily water vapor (reference) and (ii) using the climatology (estimate), followed by computing accuracy, precision, and uncertainty (APU) metrics. All APU measures were well below specification, thus the fallback usage of the climatology is generally a sound strategy. Still, the tests revealed that some considerations need to be taken into account to help quantify which sensor, band, climate, and season are most or least affected by using a fallback climatology. The highest uncertainty and bias is found for Landsat 5, with progressive improvements towards newer sensors. The bias increases from dry to humid climates, whereas uncertainty increases from dry and tropic to temperate climates. Uncertainty is smallest during seasons with low variability, and is highest when atmospheric conditions progress from a dry to a wet season (and vice versa).

Simulating Mars D/H and atmospheric chemistry during the 2018 Global Dust Storm and comparing with NOMAD observations

2020 ◽  
Author(s):  
Frank Daerden ◽  
Lori Neary ◽  
Geronimo Villanueva ◽  
Shohei Aoki ◽  
Sebastien Viscardy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Atmospheric Chemistry ◽  
Dust Storm ◽  
General Circulation ◽  
Circulation Model ◽  
Cloud Formation ◽  
Vertical Profiles ◽  
Considerable Impact ◽  
Physical And Chemical ◽  
The Impact

&lt;p&gt;The NOMAD instrument suite on the ESA-Roskosmos ExoMars Trace Gas Orbiter (TGO) observes the physical and chemical composition of the Martian atmosphere with highly resolved vertical profiles and nadir sounding in the IR and UV-vis domains. Vertically resolved profiles of, amongst other species, water vapor, HDO, ozone, CO, CO&lt;sub&gt;2&lt;/sub&gt;, oxygen airglow, dust and clouds were obtained for more than one Martian year [1-5]. During its first year of operations, NOMAD witnessed the 2018 Global Dust Storm (GDS) during its onset, peak and decline. The redistribution of water vapor to high altitudes and latitudes observed during the GDS was explained using the GEM-Mars General Circulation Model (GCM) [6-8]. The GCM was driven by the dust optical depths for Mars Year 34 provided by [9]. The photolysis products of water vapor are a major driver for the atmospheric chemistry on Mars. As water vapor is redistributed over the atmosphere, it is expected to have considerable impact on many other species. GEM-Mars contains routines for atmospheric chemistry and here we present some results of the simulated impact of the GDS on atmospheric chemistry and on several of the observed species. GEM-Mars now also includes the simulation of HDO and the fractionation of water vapor upon cloud formation. The simulations will be compared with the vertical profiles of the D/H ratio obtained from NOMAD observations. The impact of the GDS on D/H can be estimated from these simulations.&lt;/p&gt;&lt;p&gt; &amp;#160;&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;[1] Vandaele, A. C. et al. (2019), Nature, 568, 7753, 521-525, doi: 10.1038/s41586-019-1097-3.&lt;/p&gt;&lt;p&gt;[2] Aoki, S. et al. (2019), J. Geophys. Res.: Planets, 124, 3482&amp;#8211;3497. https://doi.org/10.1029/2019JE006109&lt;/p&gt;&lt;p&gt;[3] G&amp;#233;rard et al. (2020), Nature Astronomy, https://doi.org/10.1038/s41550-020-1123-2&lt;/p&gt;&lt;p&gt;[4] Villanueva et al., submitted.&lt;/p&gt;&lt;p&gt;[5] Korablev et al., 2020, in rev.&lt;/p&gt;&lt;p&gt;[6] Neary, L. and F. Daerden (2018), Icarus, 300, 458&amp;#8211;476, https://doi.org/10.1016/j.icarus.2017.09.028&lt;/p&gt;&lt;p&gt;[7] Daerden, F. et al. (2019), Icarus, 326, 197-224, doi: 10.1016/j.icarus.2019.02.030.&lt;/p&gt;&lt;p&gt;[8] Neary, L. et al. (2020), Geophys. Res. Lett., 47, e2019GL084354. https://doi.org/10.1029/2019GL084354&lt;/p&gt;&lt;p&gt;[9] Montabone, L. et al. (2019), J. Geophys. Res.: Planets. doi: 10.1029/2019JE006111.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt; &lt;div&gt;2.11.0.0&lt;/div&gt;&lt;!-- COMO-HTML-CONTENT-END --&gt; &lt;div&gt; &lt;div&gt;BIRA-IASB NOMAD team (continued):&lt;/div&gt; &lt;p&gt;S. Robert (1), L. Trompet (1), A. Mahieux (1), C. Depiesse (1), E. Neefs (1) and B. Ristic (1).&lt;/p&gt; &lt;/div&gt; &lt;!-- COMO-HTML-CONTENT-END --&gt; &lt;div class=&quot;co_mto_htmlabstract-teamMembers d-none d-md-block&quot;&gt; &lt;div class=&quot;co_mto_htmlabstract-teamMembers-name h1-special journal-contentHeaderColor header-element color-primary&quot;&gt;BIRA-IASB NOMAD team (continued):&lt;/div&gt; &lt;p&gt;S. Robert (1), L. Trompet (1), A. Mahieux (1), C. Depiesse (1), E. Neefs (1) and B. Ristic (1).&lt;/p&gt; &lt;/div&gt; &lt;p class=&quot;co_mto_htmlabstract-citationHeader&quot;&gt; &lt;strong class=&quot;co_mto_htmlabstract-citationHeader-intro&quot;&gt;How to cite:&lt;/strong&gt; Daerden, F., Neary, L., Villanueva, G., Aoki, S., Viscardy, S., Thomas, I., Vandaele, A. C., Liuzzi, G., Crismani, M., Khayat, A., Smith, M. D., Clancy, R. T., Wolff, M. J., Sandor, B. J., Whiteway, J. A., Mumma, M. J., Erwin, J., Willame, Y., and Piccialli, A. and the BIRA-IASB NOMAD team (continued): Simulating Mars D/H and atmospheric chemistry during the 2018 Global Dust Storm and comparing with NOMAD observations , Europlanet Science Congress 2020, online, 21 September&amp;#8211;9 Oct 2020, EPSC2020-371, 2020 &lt;/p&gt;

scholarly journals Surprisingly long lifetime of methacrolein oxide, an isoprene derived Criegee intermediate, under humid conditions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yen-Hsiu Lin ◽  
Cangtao Yin ◽  
Kaito Takahashi ◽  
Jim Jr-Min Lin
Keyword(s):  
Rate Coefficient ◽  
Effective Rate ◽  
Fast Reaction ◽  
Atmospheric Lifetime ◽  
Criegee Intermediates ◽  
Long Lifetime ◽  
Uv Visible ◽  
The Impact ◽  
Kinetics Of ◽  
State Concentration

AbstractOzonolysis of isoprene, the most abundant alkene, produces three distinct Criegee intermediates (CIs): CH2OO, methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO). The oxidation of SO2 by CIs is a potential source of H2SO4, an important precursor of aerosols. Here we investigated the UV-visible spectroscopy and reaction kinetics of thermalized MACRO. An extremely fast reaction of anti-MACRO with SO2 has been found, kSO2 = (1.5 ± 0.4) × 10−10 cm3 s−1 (±1σ, σ is the standard deviation of the data) at 298 K (150 − 500 Torr), which is ca. 4 times the value for syn-MVKO. However, the reaction of anti-MACRO with water vapor has been observed to be quite slow with an effective rate coefficient of (9 ± 5) × 10−17 cm3 s−1 (±1σ) at 298 K (300 to 500 Torr), which is smaller than current literature values by 1 or 2 orders of magnitude. Our results indicate that anti-MACRO has an atmospheric lifetime (best estimate ca. 18 ms at 298 K and RH = 70%) much longer than previously thought (ca. 0.3 or 3 ms), resulting in a much higher steady-state concentration. Owing to larger reaction rate coefficient, the impact of anti-MACRO on the oxidation of atmospheric SO2 would be substantial, even more than that of syn-MVKO.

scholarly journals Kinetics of dimethyl sulfide (DMS) reactions with isoprene-derived Criegee intermediates studied with direct UV absorption

2020 ◽  
Vol 20 (21) ◽  
pp. 12983-12993
Author(s):  
Mei-Tsan Kuo ◽  
Isabelle Weber ◽  
Christa Fittschen ◽  
Luc Vereecken ◽  
Jim Jr-Min Lin
Keyword(s):  
Atmospheric Chemistry ◽  
Dimethyl Sulfide ◽  
Relative Rate ◽  
High Reactivity ◽  
Rate Coefficients ◽  
Visible Absorption ◽  
Criegee Intermediates ◽  
Upper Limits ◽  
The Individual ◽  
Kinetics Of

Abstract. Criegee intermediates (CIs) are formed in the ozonolysis of unsaturated hydrocarbons and play a role in atmospheric chemistry as a non-photolytic OH source or a strong oxidant. Using a relative rate method in an ozonolysis experiment, Newland et al. (2015) reported high reactivity of isoprene-derived Criegee intermediates towards dimethyl sulfide (DMS) relative to that towards SO2 with the ratio of the rate coefficients kDMS+CI/kSO2+CI = 3.5 ± 1.8. Here we reinvestigated the kinetics of DMS reactions with two major Criegee intermediates formed in isoprene ozonolysis, CH2OO, and methyl vinyl ketone oxide (MVKO). The individual CI was prepared following the reported photolytic method with suitable (diiodo) precursors in the presence of O2. The concentration of CH2OO or MVKO was monitored directly in real time through their intense UV–visible absorption. Our results indicate the reactions of DMS with CH2OO and MVKO are both very slow; the upper limits of the rate coefficients are 4 orders of magnitude smaller than the rate coefficient reported by Newland et al. (2015) These results suggest that the ozonolysis experiment could be complicated such that interpretation should be careful and these CIs would not oxidize atmospheric DMS at any substantial level.

scholarly journals Pressure dependence of electron- and hole-consuming reactions in photocatalytic water splitting on Pt/TiO2studied by time-resolved IR absorption spectroscopy

2003 ◽  
Vol 5 (1) ◽  
pp. 7-9 ◽  
Author(s):  
Akira Yamakata ◽  
Taka-aki Ishibashi ◽  
Hiroshi Onishi
Keyword(s):  
Water Vapor ◽  
Water Splitting ◽  
Absorption Spectroscopy ◽  
The Other ◽  
Ir Absorption ◽  
Decay Kinetics ◽  
Time Resolved ◽  
Photogenerated Electrons ◽  
Reaction With Water ◽  
Kinetics Of

The decay kinetics of photogenerated electrons in the water splitting reaction on a Pt/TiO2photocatalyst was studied by time-resolved IR absorption spectroscopy. The decay of the photogenerated electrons within 2μs was decelerated when the catalyst was exposed to water vapor. The holes were consumed by the reaction with water instead of by the recombination with the electrons. On the other hand, the decay at 10–900μs was accelerated by the exposure. The electrons were consumed by the reaction with water. The rate of the hole-consuming reaction was independent of the pressure of water vapor, whereas that of the electron-consuming reaction increased with the pressure from 1 to 10 Torr. The different pressure dependences indicate different reactants involved in the oxidative and reductive reactants.

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