scholarly journals Daytime tropospheric loss of hexanal and <i>trans</i>-2-hexenal: OH kinetics and UV photolysis

2006 ◽  
Vol 6 (6) ◽  
pp. 13225-13250 ◽  
Author(s):  
E. Jiménez ◽  
B. Lanza ◽  
E. Martínez ◽  
J. Albaladejo
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Kinetic Measurements ◽  
Uv Photolysis ◽  
Photolysis Rates ◽  
Photolysis Laser ◽  
First Time ◽  
Pulsed Photolysis

Abstract. The ultraviolet (λ=250–370 nm) photolysis and the OH-initiated oxidation of hexanal and trans-2-hexenal, which are relevant atmospheric processes, have been investigated at room temperature and as a function of temperature (T=263–353 K), respectively. This kinetic study as a function of temperature is reported here for the first time. Absolute absorption cross sections (σλ) were obtained using a recently built system operating in the UV region. This work represents the first reported σλ for trans-2-hexenal. The obtained σλ allowed the estimation of the photolysis rates (J) of hexanal and trans-2-hexenal across the troposphere. Kinetic measurements of the gas-phase reaction of hydroxyl radicals (OH) with hexanal and trans-2-hexenal were performed by using the laser pulsed photolysis/laser-induced fluorescence technique. Rate coefficients kOH for both aldehydes were determined at temperatures between 263 and 353 K at 50 Torr in helium or argon bath gases. The temperature dependence of kOH for both aldehydes was found to be slightly negative. The tropospheric lifetime of hexanal and trans-2-hexenal due to the chemical removal by OH radicals has been estimated across the troposphere. The loss rate due to the OH chemical removal was compared with the estimated photolysis rates. Our results show that OH-reaction and UV photolysis are the main loss processes for these aldehydes in the troposphere. For hexanal, both processes compete across the troposphere, however, UV photolysis can contribute up to 70% to the overall loss of trans-2-hexenal.

scholarly journals Daytime tropospheric loss of hexanal and <I>trans</I>-2-hexenal: OH kinetics and UV photolysis

2007 ◽  
Vol 7 (6) ◽  
pp. 1565-1574 ◽  
Author(s):  
E. Jiménez ◽  
B. Lanza ◽  
E. Martínez ◽  
J. Albaladejo
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Kinetic Measurements ◽  
Photolysis Rates ◽  
Photolysis Laser ◽  
First Time ◽  
Pulsed Photolysis ◽  
System Operating

Abstract. The ultraviolet (λ=250–370 nm) photolysis and the OH-initiated oxidation of hexanal and trans-2-hexenal, which are relevant atmospheric processes, have been investigated at room temperature and as a function of temperature (T=263–353 K), respectively. This kinetic study as a function of temperature is reported here for the first time. Absolute absorption cross sections (σλ) were obtained using a recently built system operating in the UV region. The obtained σλ allowed the estimation of the photolysis rates (J) across the troposphere. Kinetic measurements of the gas-phase reaction of hydroxyl radicals (OH) with hexanal and trans-2-hexenal were performed by using the laser pulsed photolysis/laser-induced fluorescence technique. Rate coefficients kOH for both aldehydes were determined at temperatures between 263 and 353 K at 50 Torr in helium or argon bath gases. The temperature dependence of kOH for both aldehydes was found to be slightly negative. The tropospheric lifetime of hexanal and trans-2-hexenal due to the chemical removal by OH radicals has been estimated across the troposphere. The loss rate due to the OH chemical removal was compared with the estimated photolysis rates. Our results show that OH-reaction is the main loss process for these aldehydes in the troposphere, although photolysis is not negligible for hexanal.

scholarly journals Photolysis and oxidation by OH radicals of two carbonyl nitrates: 4-nitrooxy-2-butanone and 5-nitrooxy-2-pentanone

2019 ◽  
Author(s):  
Bénédicte Picquet-Varrault ◽  
Ricardo Suarez-Bertoa ◽  
Marius Duncianu ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
...  
Keyword(s):  
Cross Sections ◽  
Rate Constants ◽  
Branching Ratio ◽  
Quantum Yields ◽  
Organic Nitrates ◽  
Oh Radicals ◽  
Important Species ◽  
Photolysis Rates ◽  
Photolysis Frequencies ◽  
First Time

Abstract. Multifunctional organic nitrates, including carbonyl nitrates, are important species formed in NOx rich atmospheres by the degradation of VOCs. These compounds have been shown to play a key role in the transport of reactive nitrogen and consequently in the ozone budget, but also to be important components of the total organic aerosol. However, very little is known about their reactivity in both gas and condensed phases. Following a previous study we published on the gas-phase reactivity of β-nitrooxy ketones, the photolysis and the reaction with OH radicals of 4-nitrooxy-2-butanone and 5-nitrooxy-2-pentanone, respectively a β-nitrooxy ketone and a γ-nitrooxy ketone, were investigated for the first time in simulation chambers. Ambient photolysis frequencies calculated for 40° latitude North were found to be (4.2 ± 0.6) × 10−5 s−1 and (2.2 ± 0.7) × 10−5 s−1 for 4-nitrooxy-2-butanone and 5-nitrooxy-2-pentanone, respectively. These results demonstrate that photolysis is a very efficient sink for these compounds with atmospheric lifetimes of few hours. It was also concluded that, similarly to α-nitrooxy ketones, β-nitrooxy ketones have enhanced UV absorption cross sections and quantum yields equal or close to unity. γ-nitrooxy ketones have been shown to have lower enhancement of cross sections which can easily be explained by the increasing distance between the two chromophore groups. Thanks to a products study, branching ratio between the two possible photodissociation pathways are also proposed. Rate constants for the reaction with OH radicals were found to be (2.9 ± 1.0) × 10−12 cm3 molecule−1 s−1 and (3.3 ± 0.9) × 10−12 cm3 molecule−1 s−1, respectively. These experimental data are in good agreement with rate constants estimated by the SAR of Kwok and Atkinson (1995) when using the parametrization proposed by Suarez-Bertoa et al. (2012) for carbonyl nitrates. Comparison with photolysis rates suggests that OH-initiated oxidation of carbonyl nitrates is a less efficient sink that photodissociation but is not negligible in polluted area.

scholarly journals Direct and relative rate coefficients for the gas-phase reaction of OH radicals with 2-methyltetrahydrofuran at room temperature

2016 ◽  
Vol 119 (1) ◽  
pp. 5-18
Author(s):  
Ádám Illés ◽  
Mária Farkas ◽  
Gábor László Zügner ◽  
Gyula Novodárszki ◽  
Magdolna Mihályi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Relative Rate ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Relative Rate Coefficients

scholarly journals Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>3</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>

2011 ◽  
Vol 11 (21) ◽  
pp. 10837-10851 ◽  
Author(s):  
R. K. Talukdar ◽  
L. Zhu ◽  
K. J. Feierabend ◽  
J. B. Burkholder
Keyword(s):  
Relative Rate ◽  
Order Conditions ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
First Order ◽  
No3 Radical ◽  
Pseudo First Order ◽  
Arrhenius Expression ◽  
Coefficient Method

Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3 + (CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.

scholarly journals Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes

2005 ◽  
Vol 5 (12) ◽  
pp. 3433-3440 ◽  
Author(s):  
D. Rodríguez ◽  
A. Rodríguez ◽  
A. Notario ◽  
A. Aranda ◽  
Y. Díaz-de-Mera ◽  
...  
Keyword(s):  
Relative Rate ◽  
Weighted Average ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Additional Information ◽  
Relative Rate Constants ◽  
Relative Measurements ◽  
First Time ◽  
Structure Versus ◽  
Atomic Chlorine

Abstract. The reactions of Cl atoms with a series of unsaturated aldehydes have been investigated for the first time using a relative method. In order to obtain additional information for a qualitative structure versus reactivity discussion, we have also determined the rate coefficients for the reactions of atomic chlorine with their respective saturated aldehydes. These relative measurements were performed at room temperature and atmospheric pressure of air and N2, by using ethane, propene and 1-butene as reference compounds. The weighted average relative rate constants obtained, kCl±2σ (in units of cm3 molecule−1 s−1) were: trans-2-pentenal (1.31±0.19)×10−10; trans-2-hexenal (1.92±0.22)×10−10; trans-2-heptenal (2.40±0.29)×10−10; n-pentanal (2.56±0.27)×10−10; n-hexanal (2.88±0.37)×10−10; n-heptanal (3.00±0.34)×10−10. Finally, results and atmospheric implications are discussed and compared with the reactivity with OH and NO3 radicals.

scholarly journals Evaluation of the daytime tropospheric loss of 2-methylbutanal

2021 ◽  
Author(s):  
María Asensio ◽  
María Antiñolo ◽  
Sergio Blázquez ◽  
José Albaladejo ◽  
Elena Jiménez
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gaseous Products ◽  
Flight Mass Spectrometry ◽  
Atmospheric Degradation ◽  
The Impact

Abstract. Saturated aldehydes, e.g. 2-methylbutanal (2MB, CH3CH2CH(CH3)C(O)H), are emitted into the atmosphere by several biogenic sources. The first step in the daytime atmospheric degradation of 2MB involves gas-phase reactions initiated by hydroxyl (OH) radicals, chlorine (Cl) atoms and/or sunlight. In this work, we report the rate coefficients for the gas-phase reaction of 2MB with OH (kOH) and Cl (kCl) together with the photolysis rate coefficient (J) in the ultraviolet solar actinic region in Valencia (Spain) at different times of the day. The temperature dependence of kOH was described in the 263–353 K range by the following Arrhenius expression: kOH(T)=(8.88±0.41)×10-12 exp[(331±14)/T] cm3 molecule-1 s-1. At 298 K, the reported kOH and kCl are (2.68±0.07)×10-11 cm3 molecule-1 s-1 and (2.16±0.16)×10-11 cm3 molecule-1 s-1. Identification and quantification of the gaseous products of the Cl-reaction and those from the photodissociation of 2MB were carried out in a smog chamber by different techniques (Fourier transform infrared spectroscopy, proton transfer time-of-flight mass spectrometry, and gas chromatography coupled to mass spectrometry). The formation and size distribution of secondary organic aerosols formed in the Cl-reaction was monitored by a fast mobility particle sizer spectrometer. A discussion on the relative importance of the first step in the daytime atmospheric degradation of 2MB is presented together with the impact of the degradation products in marine atmospheres.

scholarly journals Rate coefficients for the gas-phase reaction of OH with <i>Z</i>-3-hexen-1-ol, 1-penten-3-ol, <i>E</i>-2-penten-1-ol, and <i>E</i>-2-hexen-1-ol between 243 and 404 K

2011 ◽  
Vol 11 (1) ◽  
pp. 2377-2405 ◽  
Author(s):  
M. E. Davis ◽  
J. B. Burkholder
Keyword(s):  
Gas Phase ◽  
Negative Temperature ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Oh Radical ◽  
Gas Phase Reaction ◽  
First Order ◽  
Unsaturated Alcohols ◽  
Temperature Dependences

Abstract. Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-3-hexen-1-ol ((Z)-CH3CH2CH=CHCH2CH2OH). (k1), 1-penten-3-ol (CH3CH2CH(OH)CH=CH2) (k2), (E)-2-penten-1-ol ((E)-CH3CH2CH=CHCH2OH) (k3), and (E)-2-hexen-1-ol ((E)-CH3CH2CH2CH=CHCH2OH) (k4), unsaturated alcohols that are emitted into the atmosphere following vegetation wounding, are reported. Rate coefficients were measured under pseudo-first-order conditions in OH over the temperature range 243–404 K at pressures between 20 and 100 Torr (He) using pulsed laser photolysis (PLP) to produce OH radicals and laser induced fluorescence (LIF) to monitor the OH temporal profile. The obtained rate coefficients were independent of pressure with negative temperature dependences that are well described by the Arrhenius expressions k1(T) = (1.3 ± 0.1) × 10−11 exp[(580 ± 10)/T]; k1(297K) = (1.06 ± 0.12) × 10−10 k2(T) = (6.8 ± 0.7) × 10−12 exp[(690 ± 20)/T]; k2(297K) = (7.12 ± 0.73) × 10−11 k3(T) = (6.8 ± 0.8) × 10−12 exp[(680 ± 20)/T]; k3(297K) = (6.76 ± 0.70) × 10−11 k4(T) = (5.4 ± 0.6) × 10−12 exp[(690 ± 20)/T]; k4(297K) = (6.15 ± 0.75) × 10−11 (in units of cm3 molecule−1 s−1). The quoted uncertainties are at the 2σ (95% confidence) level and include estimated systematic errors. The rate coefficients obtained in this study are compared with literature values where possible.

Atmospheric Chemistry of 1-Methoxy 2-Propyl Acetate: UV Absorption Cross Sections, Rate Coefficients, and Products of Its Reactions with OH Radicals and Cl Atoms

2016 ◽  
Vol 120 (45) ◽  
pp. 9049-9062 ◽  
Author(s):  
Antonia G. Zogka ◽  
Abdelwahid Mellouki ◽  
Manolis N. Romanias ◽  
Yuri Bedjanian ◽  
Mahmoud Idir ◽  
...  
Keyword(s):  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Uv Absorption ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Absorption Cross ◽  
Propyl Acetate ◽  
Cl Atoms

Rate coefficients for the gas-phase reaction of OH radicals with dimethyl sulfide: temperature and O2partial pressure dependence

2006 ◽  
Vol 8 (6) ◽  
pp. 728-736 ◽  
Author(s):  
Mihaela Albu ◽  
Ian Barnes ◽  
Karl H. Becker ◽  
Iulia Patroescu-Klotz ◽  
Raluca Mocanu ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pressure Dependence ◽  
Dimethyl Sulfide ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Phase Reaction
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