Kinetic study of the reactions of Br2 with OH and OD

Bedjanian, Yuri; Bras, G. Le; Poulet, G.

doi:10.1002/(sici)1097-4601(1999)31:10<698::aid-jck3>3.0.co;2-o

Cited by 34 publications

(65 citation statements)

References 19 publications

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“…Reaction (4) leads to simultaneous production of OH radicals, which may be rapidly scavenged by Br 2 (when added simultaneously with NO) through Reaction (5), forming HOBr (Bedjanian et al, 1999b): In the present study, the HO 2 detection at m/z = 46 (NO + 2 ) and m/z = 96/98 (HOBr + ) was preferred to the detection at its parent peak (m/z = 33, HO + 2 ), since the sensitivity of the mass spectrometer at these masses was higher and corresponding MS signals were free of contributions of other species and, consequently, did not require any corrections. It should be mentioned that the concentrations of HO 2 determined through [NO 2 ] and [HOBr] measurements were found to be in agreement within 10 %.…”

Section: Generation Of Ho 2 Radicals and Measurement Of Absolute Concsupporting

confidence: 87%

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

2013

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Abstract. The interaction of HO2 radicals with solid films of Arizona Test Dust (ATD) was studied using a low-pressure flow reactor (1–9 Torr) combined with a modulated molecular beam mass spectrometer for monitoring of the gaseous species involved. The reactive uptake coefficient of HO2 was measured from the kinetics of HO2 consumption on Pyrex rods coated with ATD as a function of HO2 concentration ((0.35–3.30) × 1012 molecule cm−3), relative humidity (RH = 0.02–94%), temperature (T = 275–320 K) and UV irradiance intensity (JNO2 = 0–0.012 s−1). The initial uptake coefficient was found to be independent of concentration of HO2, temperature and irradiation conditions, and to decrease with increasing relative humidity: γ0 = 1.2/(18.7 + RH1.1) (with 30% estimated conservative uncertainty). The uptake coefficient was calculated using geometric surface area and should be considered as an upper limit of γ0. An upper limit of 5% was found for the gaseous H2O2-forming pathway of the HO2 reaction with ATD surface. The results of the measurements indicate that HO2 loss on dust aerosol may be a non-negligible sink for HOx species in the troposphere with the effect depending on specific local conditions.

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Section: Generation Of Ho 2 Radicals and Measurement Of Absolute Concsupporting

confidence: 87%

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

2013

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“…The photolysis laser fluence was varied over the range (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) mJ pulse -1 cm -2 . The OH probe laser fluence ranged from 0.2 to 0.4 mJ pulse -1 cm -2 .…”

Section: Methodssupporting

confidence: 61%

Rate Coefficient and Product Branching Measurements for the Reaction OH + Bromopropane from 230 to 360 K

et al. 2002

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Rate coefficients over the range of 230-360 K were measured for the reaction of OH with the following bromopropane isotopomers: CH 3 CH 2 CH 2 Br (k 1 ), CD 3 CH 2 CH 2 Br (k 2 ), CD 3 CH 2 CD 2 Br (k 3 ), CH 3 CD 2 CD 2 Br (k 4 ), and CD 3 CD 2 CD 2 Br (k 5 ). The hydroxyl radical was produced by pulsed laser photolysis and detected via laser induced fluorescence. Reaction 1 can occur by H atom abstraction from three different carbon sites: OH + CH 3 CH 2 CH 2 Br f CH 3 CH 2 CHBr + H 2 O (1a; R); f CH 3 CHCH 2 Br + H 2 O (1b; ); or f CH 2 CH 2 -CH 2 Br + H 2 O (1c; γ). Branching ratios obtained from an analysis of the kinetic data at 298 K are k 1c /k 1 ) 0.12 ( 0.08, k 1b /k 1 ) 0.56 ( 0.04, and k 1a /k 1 ) 0.32 ( 0.08; uncertainties given are 2 standard deviations and do not include systematic uncertainties. Stable products formed following reaction 1 in a NO x /O 2 environment were measured using long path infrared absorption. Bromoacetone and propanal were observed in the ratio [(CH 3 C(O)CH 2 Br)/(CH 3 CH 2 CHO)] of 1.65 ( 0.50 with an absolute bromoacetone yield of 0.5 ( 0.2 at room temperature. The product yields are consistent with the rate coefficient data. Ab initio calculations show that C-H bond energies at both the R and sites decrease (relative to propane) by the addition of Br at the R site. The calculated transition state energies decrease in the order γ > R > , in qualitative agreement with the experimental observations.

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“…To our knowledge, all previous direct kinetic studies [5][6][7][8][9] of the reaction of OH + Br 2 have been performed at low temperatures. Data reported in references 5 and 6 were measured at room temperature only.…”

Section: Comparison With Previous Studies and Discussionmentioning

confidence: 99%

“…[7][8][9] Boodaghians et al 7 measured k 1 at four temperatures only over the temperature range of 262 -303 K. As can be seen from Figure 3 these k 1 data are systematically lower than ours and those from references 5-9 in the common temperature intervals, but they are in agreement with them near room temperature within the experimental uncertainties. Their data show a slight positive temperature dependence (see Figure 3).…”

Section: Comparison With Previous Studies and Discussionmentioning

confidence: 99%

“…Measurements performed in references 8 and 9 showed a distinct, albeit weak, negative temperature dependences k 1 9 These data are in agreement with equation III within the reported experimental uncertainties and can be combined with the current experimental k 1 (T) data set. Indeed, if our k 1 (T) data set is combined with the k 1 (T) data sets from references 8, 9, then the least-squares fit of the resultant combined set of data to the equation of the form k 1 (T) = AT n yields the expression…”

Section: Comparison With Previous Studies and Discussionmentioning

confidence: 99%

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Kinetic Study of the Gas-Phase Reaction of OH with Br₂

2006

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An experimental, temperature-dependent kinetic study of the gas-phase reaction of the hydroxyl radical with molecular bromine (reaction 1) has been performed using a pulsed laser photolysis/ pulsed-laser-induced fluorescence technique over a wide temperature range of 297 -766 K, and at pressures between 6.68 and 40.29 kPa of helium. The experimental rate coefficients for reaction 1 demonstrate no correlation with pressure and exhibit a negative temperature dependence with a slight negative curvature in the Arrhenius plot. A non-linear least-squares fit with two floating parameters of the temperature dependent k 1 (T) data set using an equation of the form k 1 (T) = AT n yields the recommended expression k 1 (T) = 1.85×10 −9 T − 0.66 cm 3 molecule −1 s −1 for the temperature dependence of the reaction 1 rate coefficient. The potential energy surface (PES) of reaction 1 was investigated using quantum chemistry methods. The reaction proceeds through formation of a weakly bound OH···Br 2 complex and a PES saddle point with an energy below that of the reactants. Temperature dependence of the reaction rate coefficient was modeled using the RRKM method on the basis of the calculated PES.

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Kinetic study of the reactions of Br2 with OH and OD

Cited by 34 publications

References 19 publications

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

Rate Coefficient and Product Branching Measurements for the Reaction OH + Bromopropane from 230 to 360 K

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

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Kinetic study of the reactions of Br2 with OH and OD

Cited by 34 publications

References 19 publications

Uptake of HO&lt;sub&gt;2&lt;/sub&gt; radicals on Arizona Test Dust

Uptake of HO&lt;sub&gt;2&lt;/sub&gt; radicals on Arizona Test Dust

Rate Coefficient and Product Branching Measurements for the Reaction OH + Bromopropane from 230 to 360 K

Kinetic Study of the Gas-Phase Reaction of OH with Br2

Contact Info

Product

Resources

About

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

Uptake of HO<sub>2</sub> radicals on Arizona Test Dust

Kinetic Study of the Gas-Phase Reaction of OH with Br₂