Bromine photosensitized decomposition of ozone

Jaffe, S.; Mainquist, W. K.

doi:10.1021/j100461a030

Cited by 16 publications

(15 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover in the presence of excess ozone, any bromine atoms produced in channel 1a of the BrO + BrO reaction are rapidly reconverted into BrO by reaction with ozone. Consequently, this channel has no effect on the observed BrO kinetics, and the observed BrO decay represents channel (1b) only, as has been verified in several previous studies: [4][5][6][7][8][9][10][11][12][13][14] However, as described by Rowley Furthermore, the reaction between Br atoms and ozone (3) has a positive temperature dependence 17 whereas that between Br and BrO accelerates rapidly at low temperatures. 26 Thus, experiments carried out in this work at low temperatures were performed with concentrations of ozone high enough to ensure that any Br atoms formed in channel 1a were consumed by ozone and not by BrO.…”

Section: Photolysis Of Br 2 In the Presence Of Osupporting

confidence: 74%

Kinetics and Mechanism of the BrO Self-Reaction: Temperature- and Pressure-Dependent Studies

et al. 1998

View full text Add to dashboard Cite

The flash photolysis/UV absorption technique has been used to study the self-reaction of BrO radicals over the temperature range 222-298 K and the pressure range 100-760 Torr of N 2 or O 2 . Two chemical sources of BrO radicals were used: photolysis of Br 2 in the presence of excess ozone and photolysis of O 2 in the presence of excess Br 2 . The overall rate constant, k 1 , for the BrO self-reaction (defined by -d[BrO]/dt ) 2k 1 [BrO] 2 ) was found to be temperature and pressure independent at T g 250 K, with k 1 ) (2.88 ( 0.20) × 10 -12 cm 3 molecule -1 s -1 . At temperatures below 250 K, k 1 was found to be pressure dependent, due to the emergence of a new termolecular channel of the BrO self-reaction 1c, -1c forming the BrO dimer, Br 2 O 2 (BrO + BrO + M h Br 2 O 2 + M). Channel-specific rate constants were determined for the two bimolecular channels of the BrO self-reaction above 250 K, giving for (1a) (BrO + BrO f 2Br + O 2 ) k 1a ) (5.31 ( 1.17) × 10 -12 exp{(-211 ( 59)/T} cm 3 molecule -1 s -1 and for (1b) (BrO + BrO f Br 2 + O 2 ) k 1b ) (1.13 ( 0.47) × 10 -14 exp{(983 ( 111)/T} cm 3 molecule -1 s -1 . Below 250 K, the overall rate coefficient of the two bimolecular channels is reduced as the dimer forming channel emerges. At 235 and 222 K, rate constants for the formation (k 1c ) and decomposition (k -1c ) of Br 2 O 2 were recorded. Using the values for K 1c , ∆H r for reaction 1c was estimated as -58.6 ( 0.1 kJ mol -1 . A UV absorption spectrum attributed to Br 2 O 2 was also recorded over the wavelength range 300-390 nm. The cross section of the smooth Br 2 O 2 spectrum was found to be 1.2 × 10 -17 cm 2 molecule -1 at 320 nm. These results are rationalized in terms of a mechanism of the BrO self-reaction that shows competition, at low temperatures, between collisional quenching and unimolecular dissociation of an excited BrOOBr* intermediate. The rate constant for the reaction of oxygen atoms with molecular bromine was also determined in the course of these experiments [O + Br 2 f BrO + Br (5)], giving k 5 ) (5.12 ( 1.86) × 10 -13 exp{(989 ( 91)/T} cm 3 molecule -1 s -1 . All errors are 1σ. The atmospheric implications of these results are discussed.

show abstract

Section: Photolysis Of Br 2 In the Presence Of Osupporting

confidence: 74%

Kinetics and Mechanism of the BrO Self-Reaction: Temperature- and Pressure-Dependent Studies

et al. 1998

View full text Add to dashboard Cite

show abstract

“…All the results of temperature-dependent measurements of k 1a /k 1 are shown in Figure 6. The data shown in Figure 6 are those measured through Br 2 -photosensitized decomposition of ozone 6,8,13 and calculated using reported values of k 1a and k 1 [Ref. 18] or k 1b and k 1 (this work).…”

Section: Branching Ratio K 1a /Kmentioning

confidence: 96%

“…The kinetics of the self‐reaction of BrO

BrO + BrO \to Br + Br + {normalO}_{2},

BrO + BrO \to B {normalr}_{2} + {normalO}_{2},

BrO + BrO false(+ M false) \to B {normalr}_{2} {normalO}_{2} false(+ M false) .

has been studied very extensively in the past 5‐18 . All the available temperature‐dependent measurements indicate a negative temperature dependence of the total rate constant ( k 1 = k 1a + k 1b + k 1c ); however, the absolute values of k 1 differ by a factor of 1.6 7,9,13,15,18 .…”

Section: Introductionmentioning

confidence: 99%

“…has been studied very extensively in the past. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] All the available temperature-dependent measurements indicate a negative temperature dependence of the total rate constant (k 1 = k 1a + k 1b + k 1c ); however, the absolute values of k 1 differ by a factor of 1.6. 7,9,13,15,18 Current evaluations of the kinetics 19,20 recommend rate constants based on the largest of the measured values of k 1 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rate constant of the BrO + BrO reaction over the temperature range 220‐950 K

Bedjanian

2020

Int J of Chemical Kinetics

View full text Add to dashboard Cite

The kinetics of the self‐reaction of BrO radicals has been studied over a wide temperature range (T = 220‐950 K) at 2 Torr total pressure of He using a low‐pressure flow reactor combined with a quadrupole mass spectrometer: BrO + BrO → 2Br + O2 (1a) and BrO + BrO → Br2 + O2 (1b). The overall rate constant for this reaction (defined by d[BrO]/dt = –2k1[BrO]2) was found to be k1 = k1a +k1b = (1.32 ± 0.09) × 10−12 exp(182 ± 22/T) cm3 molecule−1 s−1 at T = 220‐950 K (where the uncertainties represent precision at the 2σ level). The channel‐specific rate constant for the Br2 + O2 forming channel (1b) was determined at T = 220‐450 K: k1b = (2.83 ± 0.35) × 10−13 exp(34 ± 36/T) cm3 molecule−1 s−1 (with 2σ uncertainties). As a result of the comparative analysis of the present data and those from the previous studies, the following Arrhenius expressions are recommended from the present work: k1 = 1.4 × 10−12 exp(200/T) at T = 220‐950 K (independent of pressure at least for T ≥ 250 K) and k1b = 3.2 × 10−13 exp(34/T) cm3 molecule−1 s−1 at T = 220‐450 K and total pressure of 2 Torr, with a conservative estimate of uncertainty of 25%, independent of temperature.

show abstract

“…[4][5][6][7] However, liquid and neutral-polymer electrolyte materials consisting of simultaneously mobile anions and cations exhibit performance-hampering charge polarization as a result of the coordinated diffusion of counterions and subsequent buildup of anions near the anode. [8][9][10] In such a context, single-ion conductors (SICs), representing materials in which either the anions or cations are covalently attached to a macromolecule of low mobility, have been proposed as a solution. In such materials, the coordinated diffusion of the ion pairs is significantly reduced, and as a result, the charge polarization effects are virtually eliminated, resulting in transference numbers close to unity.…”

mentioning

confidence: 99%

Influence of side chain linker length on ion‐transport properties of polymeric ionic liquids

Keith

Mogurampelly

Wheatle

et al. 2017

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

We used atomistic molecular dynamics simulations to study the properties of polymerized 1‐alkene‐3‐butylimidazolium‐hexafluorophosphate, a polymerized ionic liquid electrolyte, and characterized the influence of the linear alkene length on the mobility of the hexafluorophosphate ions. Consistent with experimental observations, our simulations indicate that as the alkene length increases, the diffusivity of hexafluorophosphate anion monotonically increases. We demonstrate that such a trend arises from the influence of linker segments on the intermolecular ion hopping rates, which is in turn modulated by intermolecular cationic separation distances. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1718–1723

show abstract

Bromine photosensitized decomposition of ozone

Cited by 16 publications

References 1 publication

Kinetics and Mechanism of the BrO Self-Reaction: Temperature- and Pressure-Dependent Studies

Kinetics and Mechanism of the BrO Self-Reaction: Temperature- and Pressure-Dependent Studies

Rate constant of the BrO + BrO reaction over the temperature range 220‐950 K

Influence of side chain linker length on ion‐transport properties of polymeric ionic liquids

Contact Info

Product

Resources

About