Kinetic studies of the bromine-oxygen system: A new paramagnetic particle, BrO2

Butkovskaya, N. I.; Morozov, I. I.; Talrose, V.L.; Vasiliev, E. S.

doi:10.1016/0301-0104(83)85135-0

Cited by 33 publications

(25 citation statements)

References 12 publications

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“…8,19 The detailed formation mechanisms are not known but wall reactions play a key role in the formation and interconversion of the bromine oxides, and the primary products may be both OBrO and The Br 2 O.20 surface reactions appear to require the presence of O(3P) and/or metastable oxygen 1&) from the microwave dis-O 2 (1*, charge. In order to characterize the products of the wall reactions occurring in the Ñow reactor, separate experiments were carried out using similar discharge-Ñow systems coupled to UVÈVIS and submillimeter absorption spectrometers.…”

Section: Temperature Dependence Of the Rate Coefficient For Reaction (3)mentioning

confidence: 99%

Kinetics of the HO2+BrO reaction over the temperature range 233–348 K

Li¹,

Friedl²,

Sander³

1997

Faraday Trans.

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The reaction is the rate-limiting step in a key catalytic ozone destruction cycle in the lower stratosphere. BrO ] HO 2 ] products In this study a discharge-Ñow reactor coupled with molecular beam mass spectrometry has been used to study the BrO ] HO 2 reaction over the temperature range 233È348 K. Rate constants were measured under pseudo-Ðrst-order conditions in separate experiments with Ðrst and then BrO in excess in an e †ort to identify possible complications in the reaction conditions. At HO 2 298 K, the rate constant was determined to be (1.73^0.61) ] 10~11 cm3 molecule~1 s~1 with in excess and HO 2 (2.05^0.64) ] 10~11 cm3 molecule~1 s~1 with BrO in excess. The combined results of the temperature-dependent experiments gave the following Ðt to the Arrhenius expression : k \ (3.13^0.33) ] 10~12 exp(536^206/T ) where the quoted uncertainties represent two standard deviations. The reaction mechanism is discussed in light of recent ab initio results on the thermochemistry of isomers of possible reaction intermediates.

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Section: Temperature Dependence Of the Rate Coefficient For Reaction (3)mentioning

confidence: 99%

Kinetics of the HO2+BrO reaction over the temperature range 233–348 K

Li¹,

Friedl²,

Sander³

1997

Faraday Trans.

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“…They detected the paramagnetic OBrO molecule with a lifetime >10 s among the products of the reaction O( 3 P) + Br 2 in a discharge flow system operated at room temperature and a total pressure of 4 Torr. Further experiments, in which Br 2 was introduced at the upstream end of the flow tube (with a reaction time of about 0.1s), showed that the OBrO signal increased when the O-atom source was turned off. This observation was interpreted as evidence for the reaction of OBrO with O( 3 P) and for accumulation of OBrO on the wall of the flow tube.…”

Section: Introductionmentioning

confidence: 99%

“…The first observation of gas-phase OBrO in the laboratory was reported by Butkovskaya et al using the discharge flow−mass spectrometry technique. Flow tube effluent was passed through a nozzle-skimmer to form a molecular beam, focused through an inhomogeneous magnetic field to select paramagnetic species such as Br and OBrO, and then subjected to mass spectrometric detection.…”

Section: Introductionmentioning

confidence: 99%

Photoionization Efficiency Spectrum and Ionization Energy of OBrO

Thorn¹,

Stief²,

Buckley³

et al. 1999

J. Phys. Chem. A

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The photoionization efficiency (PIE) spectrum of OBrO was measured over the wavelength range λ ) 86-126 nm using a discharge flow-photoionization mass spectrometer (DF-PIMS) apparatus coupled to a VUV synchrotron radiation source. Bromine dioxide was generated in a flow tube reactor by first forming BrO via the reaction O( 3 P) + Br 2 and then allowing the BrO to react on the cold flow tube wall. The PIE spectrum of the BrO reactant was obtained and the photoionization threshold evaluated from the half-rise point of the step at threshold. This remeasurement yields IE(BrO) ) 10.48 ( 0.02 eV, which supersedes our previous result. The PIE spectrum of OBrO displayed steplike behavior near threshold. A value of 10.29 ( 0.03 eV was obtained for the adiabatic ionization energy (IE) of OBrO from analysis of the photoionization threshold at λ ) 120.5 nm. An ab initio determination of the IE of OBrO using the CCSD(T)/6-311+G(3df)//CCD/ 6-311+G(3df) level of theory gives a value of 10.26 ( 0.06 eV, which is in excellent agreement with the experimental result. The results are compared with previous determinations of the IE for both halogen monoxides, XO, and halogen dioxides, OXO (X ) Cl, Br, I).

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“…11 Regarding bromine dioxides, OBrO is known to be much less stable than OClO, and before 1990 it was only observed at low temperatures in the condensed phase. 12 This symmetrical dioxide was detected in 1990 in the gas phase in the reaction of Br 2 with atomic oxygen 13 and identified as a paramagnetic molecule with C 2V symmetry. The visible spectrum of gaseous OBrO has been reported only in 1994, 14 and spectroscopic evidence of its formation as an intermediate in the BrO + O 3 reaction was presented very recently.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Study of Bromine Dioxides OBrO and BrOO

Pacios

Gómez

1997

J. Phys. Chem. A

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Bromine dioxides OBrO and BrOO are theoretically studied by means of valence-only ab initio correlated calculations using TZ(2df) basis sets generated for O, Cl, and Br atoms, especially optimized for averaged relativistic effective core potentials (AREP). Equilibrium geometries for these dioxides are obtained using UMP2 and CCSD(T) electron correlation methods, while harmonic frequencies and dipole moments are computed at the UMP2/AREP/TZ(2df) level. The effect of spin contamination on UMP2 results for geometries and frequencies in these doublet radicals is also discussed. All the analyses dealing with energies are based on CCSD and CCSD(T) calculations. The energetic ordering of both bromine dioxides as well as the two possible dissociation channels, Br + O 2 and BrO + O, are discussed. The nature of the bonding in the energetically more stable BrOO isomer is also investigated by studying its energy surface; a small barrier between 1.2 and 1.7 kcal/mol for this dioxide dissociating into Br + O 2 is predicted.

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Kinetic studies of the bromine-oxygen system: A new paramagnetic particle, BrO2

Cited by 33 publications

References 12 publications

Kinetics of the HO2+BrO reaction over the temperature range 233–348 K

Kinetics of the HO2+BrO reaction over the temperature range 233–348 K

Photoionization Efficiency Spectrum and Ionization Energy of OBrO

Ab Initio Study of Bromine Dioxides OBrO and BrOO

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