Bromine Monoxide Research Articles

Bromine oxide—ozone interaction over the Dead Sea

Atmospheric measurements were performed during a 1 month period in early summer of 1997 at the Dead Sea in Israel in an attempt to identify bromine monoxide BrO, and evaluate its effect on ozone chemistry. The differential optical absorption spectroscopy (DOAS) technique was utilized to identify and measure BrO present in the air masses. Concurrent to the DOAS measurements, continuous monitoring of SO2, NO/NOx, O3, and CO was performed. Filter samples for aerosol analysis and whole air canister samples for bromocarbon analysis were also collected. The present paper reports the complete comprehensive data set of the measurements at the Dead Sea site and is a continuation to our preliminary communication [Heberstreit et al., 1999]. The more complete data now available enable a more detailed examination of the sources and mechanisms of the reactive halogen species and the presentation of new conclusions. The results showed a diurnal repeating cycle of O3 and BrO variations, correlated with solar radiation and wind direction. During the elevated BrO events, where bromine oxide rose to daily maximum values often exceeding 100 ppt, a clear negative correlation with O3 was observed. During these episodes, the O3 regularly decreased from noontime levels of 50–80 ppb or higher down to 10–30 ppb and occasionally to levels below the detection limit of 2 ppb. The enhanced BrO levels were associated with southerly winds that are typical for the location during midday hours. This suggests that a possible source for the reactive bromine species is the interaction of atmospheric oxidants with bromide at the surface of the large salt pans located at the southern end of the Dead Sea. Research flights flown over the area showed that ozone destruction to levels well below the background values were observed over large areas of the Dead Sea Valley.

An Investigation of the Structures, Vibrational Spectra, and Relative Energetics of CH3COBrO3 Isomers

The structures, vibrational spectra, and relative energetics of CH3COBrO3 isomers have been examined using the B3LYP method in conjunction with different basis sets. The CH3COOBrO2 structural form is found to possess the lowest energy with an estimated heat of formation of −38.2 kcal mol-1, at 0 K, as determined from G2MP2 theory. The next lowest energy structural form is CH3COOOOBr, which lies 7.7 kcal mol-1 above CH3COOBrO2. The isomeric forms possessing higher energies are CH3COOOBrO and CH3COBrO3. We have examined the implication of the formation of CH3COBrO3 isomers from the atmospheric cross-reactions of the acetylperoxy (CH3COO2) and bromine monoxide (BrO) radicals and determined the possible dissociation products of the most likely CH3COBrO3 isomers.

The role of bromine and chlorine chemistry for arctic ozone depletion events in Ny-Ålesund and comparison with model calculations

Abstract. During the Arctic Tropospheric Ozone Chemistry (ARCTOC) campaigns at Ny-Ålesund, Spitsbergen, the role of halogens in the depletion of boundary layer ozone was investigated. In spring 1995 and 1996 up to 30 ppt bromine monoxide were found whenever ozone decreased from normal levels of about 40 ppb. Those main trace gases and others were specifically followed in the UV-VIS spectral region by differential optical absorption spectroscopy (DOAS) along light paths running between 20 and 475 m a.s.l.. The daily variation of peroxy radicals closely followed the ozone photolysis rate J(O3(O1D)) in the absence of ozone depletion most of the time. However, during low ozone events this close correlation was no longer found because the measurement of radicals by chemical amplification (CA) turned out to be sensitive to peroxy radicals and ClOx. Large CA signals at night can sometimes definitely be assigned to ClOx and reached up to 2 ppt. Total bromine and iodine were both stripped quantitatively from air by active charcoal traps and measured after neutron activation of the samples. Total bromine increased from background levels of about 15 ppt to a maximum of 90 ppt during an event of complete ozone depletion. For the spring season a strong source of bromine is identified in the pack ice region according to back trajectories. Though biogenic emission sources cannot be completely ruled out, a primary activation of halogenides by various oxidants seems to initiate an efficient autocatalytic process, mainly driven by ozone and light, on ice and perhaps on aerosols. Halogenides residing on pack ice surfaces are continuously oxidised by hypohalogenous acids releasing bromine and chlorine into the air. During transport and especially above open water this air mixes with upper layer pristine air. As large quantities of bromine, often in the form of BrO, have been observed at polar sunrise also around Antarctica, its release seems to be a natural phenomenon. The source strength of bromine from halogen activation on the pack ice, as based on the measured inorganic bromine levels, averages about 1012 Br-atoms m-2 s-1 during sunlit periods in Arctic spring. The total source strength of inorganic bromine from sunlit polar regions may therefore amount to 30 kt y-1.Key words. Atmospheric composition and structure (troposphere · composition and chemistry; instruments and techniques)

Evidence for bromine monoxide in the free troposphere during the Arctic polar sunrise

During the Arctic polar springtime, dramatic ozone losses occur not only in the stratosphere but also in the underlying troposphere1. These tropospheric ozone loss events have been observed over large areas2,3 in the planetary boundary layer (PBL) throughout the Arctic4,5. They are associated with enhanced concentrations of halogen species1,6,7,8,9 and are probably caused by catalytic reactions involving bromine monoxide (BrO) and perhaps also chlorine monoxide (ClO)1,10,11,12. The origin of the BrO, the principle species driving the ozone destruction, is thought to be the autocatalytic release of bromine from sea salt accumulated on the Arctic snow pack10,11,13, followed by photolytic and heterogeneous reactions which produce and recycle the oxide10,11,14,15. Satellite observations have shown the horizontal and temporal extent of large BrO enhancements in the Arctic troposphere16,17, but the vertical distribution of the BrO has remained uncertain. Here we report BrO observations obtained from a high-altitude aircraft that suggest the presence of significant amounts of BrO not only in the PBL but also in the free troposphere above it. We believe that the BrO is transported from the PBL into the free troposphere through convection over large Arctic ice leads (openings in the pack ice). The convective transport also lifts ice crystals and water droplets well above the PBL18,19, thus providing surfaces for heterogeneous reactions that can recycle BrO from less-reactive forms and thereby maintain its ability to affect the chemistry of the free troposphere.

Bromine explosion

Bromine free radicals are emerging as important players in the photochemistry of the lower atmosphere, at least on local scales. Earlier this month, Hebestreit et al. described the discovery of air laden with bromine monoxide (BrO) wafting off the salt pans near the Dead Sea. And on page 338 of this issue, McElroy and colleagues report observations of BrO, obtained by remote measurements in the Arctic, that suggest bromine is present between the tropopause (at about 8 km height) and the top of the planetary boundary layer (~1 km). The planetary boundary layer is unlike the free troposphere that lies above it because the turbulence mixing timescale is very fast, and so exchange of gases with the surface occurs quickly (less than 1 day).

The role of bromine and chlorine chemistry for arctic ozone depletion events in Ny-Ålesund and comparison with model calculations

During the Arctic Tropospheric Ozone Chemistry (ARCTOC) campaigns at Ny-à lesund, Spitsbergen, the role of halogens in the depletion of boundary layer ozone was investigated. In spring 1995 and 1996 up to 30 ppt bromine monoxide were found whenever ozone decreased from normal levels of about 40 ppb. Those main trace gases and others were specifically followed in the UV-VIS spectral region by differential optical absorption spectroscopy (DOAS) along light paths running between 20 and 475 m a.s.l.. The daily variation of peroxy radicals closely followed the ozone photolysis rate J(O3(O1D)) in the absence of ozone depletion most of the time. However, during low ozone events this close correlation was no longer found because the measurement of radicals by chemical amplification (CA) turned out to be sensitive to peroxy radicals and ClOx. Large CA signals at night can sometimes definitely be assigned to ClOx and reached up to 2 ppt. Total bromine and iodine were both stripped quantitatively from air by active charcoal traps and measured after neutron activation of the samples. Total bromine increased from background levels of about 15 ppt to a maximum of 90 ppt during an event of complete ozone depletion. For the spring season a strong source of bromine is identified in the pack ice region according to back trajectories. Though biogenic emission sources cannot be completely ruled out, a primary activation of halogenides by various oxidants seems to initiate an efficient autocatalytic process, mainly driven by ozone and light, on ice and perhaps on aerosols. Halogenides residing on pack ice surfaces are continuously oxidised by hypohalogenous acids releasing bromine and chlorine into the air. During transport and especially above open water this air mixes with upper layer pristine air. As large quantities of bromine, often in the form of BrO, have been observed at polar sunrise also around Antarctica, its release seems to be a natural phenomenon. The source strength of bromine from halogen activation on the pack ice, as based on the measured inorganic bromine levels, averages about 1012 Br-atoms m-2 s-1 during sunlit periods in Arctic spring. The total source strength of inorganic bromine from sunlit polar regions may therefore amount to 30 kt y-1.Key words. Atmospheric composition and structure (troposphere · composition and chemistry; instruments and techniques)

Groundbased measurements of stratospheric OClO, NO2, and O3 at Søndre Strømfjord in winter 1991/92

Experiment (EASOE) campaign Within the scope of the 1991/92 European Arctic Stratospheric Ozone stratospheric chlorine dioxide, OClO, nitrogen dioxide, NO2, bromine monoxide, BrO, and ozone, O3, were measured by groundbased UV‐VIS remote sensing in Søndre Strømfjord, Greenland (50.4°W, 67.0°N). The measurement period was from the middle of November 1991 until the end of January 1992. The anticipated correlation between potential vorticity and OClO appeared less pronounced in the beginning and its abundance was similar inside and outside of the polar vortex. During November 1991 stratospheric temperatures throughout the polar region were still above threshold for polar stratospheric cloud (PSC) formation. During January when NO2 column densities were at their lowest, OClO inside of the vortex appeared to be highly variable. Average vertical column densities reached about 1013 molec cm−2, less than found in previous years.The chemistry as well as the observations may have been disturbed by the aerosol cloud from Mt. Pinatubo eruption.

Chemical Loss of Ozone in the Arctic Polar Vortex in the Winter of 1991-1992

In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.

Kinetics and temperature dependence of the bromine monoxide + chlorine monoxide reaction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and temperature dependence of the bromine monoxide + chlorine monoxide reactionAndrew A. Turnipseed, John W. Birks, and Jack G. CalvertCite this: J. Phys. Chem. 1991, 95, 11, 4356–4364Publication Date (Print):May 1, 1991Publication History Published online1 May 2002Published inissue 1 May 1991https://doi.org/10.1021/j100164a035RIGHTS & PERMISSIONSArticle Views98Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Kinetics of the bromine monoxide radical + bromine monoxide radical reaction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the bromine monoxide radical + bromine monoxide radical reactionAndrew A. Turnipseed, John W. Birks, and Jack G. CalvertCite this: J. Phys. Chem. 1990, 94, 19, 7477–7482Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 September 1990https://doi.org/10.1021/j100382a032RIGHTS & PERMISSIONSArticle Views91Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (700 KB) Get e-Alerts

Kinetics and products of the bromine monoxide + chlorine monoxide reaction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and products of the bromine monoxide + chlorine monoxide reactionG. Poulet, I. T. Lancar, G. Laverdet, and G. Le BrasCite this: J. Phys. Chem. 1990, 94, 1, 278–284Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://doi.org/10.1021/j100364a046RIGHTS & PERMISSIONSArticle Views83Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (874 KB) Get e-Alerts

In situ observations of BrO over Antarctica: ER‐2 aircraft results From 54°S to 72°S latitude

Bromine monoxide was observed in situ during nine flights of the NASA ER‐2 aircraft from Punta Arenas, Chile (54°S latitude), to 72°S latitude over the Palmer Peninsula, Antarctica. The first flight for the BrO detection system was on August 28. The distribution of BrO inside the chemically perturbed region defined by greatly elevated ClO abundances was different from that found just outside. Inside, the BrO mixing ratio was 6.1±1.1 pptv above the 440 K potential temperature surface, 4.7±2.0 pptv between the 400 and 440 K surfaces, and less than 4 pptv below the 400 K surface. At high latitudes outside the chemically perturbed region, the BrO mixing ratio was 5.4±1.4 pptv near the 450 K surface, but decreased to 2.9±1.2 pptv at the 420 K surface. The abundance of BrO showed no discernible temporal trend during the course of the nine flights. Away from the south polar region, at latitudes between 47°S and 37°N and potential temperatures between 435 and 500 K (18.5‐ to 20.7‐km altitude), the BrO mixing ratio was 0.5–3.0 pptv.

Discharge flow kinetic study of the reactions of nitrate radical with bromine, bromine monoxide, hydrogen bromide, and hydrogen chloride

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDischarge flow kinetic study of the reactions of nitrate radical with bromine, bromine monoxide, hydrogen bromide, and hydrogen chlorideA. Mellouki, G. Poulet, G. Le Bras, R. Singer, J. P. Burrows, and G. K. MoortgatCite this: J. Phys. Chem. 1989, 93, 24, 8017–8021Publication Date (Print):November 1, 1989Publication History Published online1 May 2002Published inissue 1 November 1989https://doi.org/10.1021/j100361a012RIGHTS & PERMISSIONSArticle Views69Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (586 KB) Get e-Alerts

Kinetics and product studies of the reaction chlorine monoxide + bromine monoxide using flash photolysis-ultraviolet absorption

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and product studies of the reaction chlorine monoxide + bromine monoxide using flash photolysis-ultraviolet absorptionStanley P. Sander and Randall R. FriedlCite this: J. Phys. Chem. 1989, 93, 12, 4764–4771Publication Date (Print):June 1, 1989Publication History Published online1 May 2002Published inissue 1 June 1989https://doi.org/10.1021/j100349a017RIGHTS & PERMISSIONSArticle Views147Altmetric-Citations59LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (938 KB) Get e-Alerts

Kinetics and product studies of the reaction chlorine monoxide + bromine monoxide using discharge-flow mass spectrometry

The kinetics and product branching ratios of the reaction between ClO and BrO were studied at 1 torr pressure over the temperature range 220-400 K, using the method of discharge-flow mass spectrometry. Three product channels were identified and quantified: Br + ClOO, Br + OClO, and BrCl + O2, indicating that the reaction mechanism of ClO + BrO involves metastable intermediates. The overall reaction rate coefficient and the rate coefficients for the three channel reactions are given.

In Situ Northern Mid-Latitude Observations of ClO, O 3 , and BrO in the Wintertime Lower Stratosphere

In order to test photochemical theories linking chlorofluorocarbon derivatives to ozone(O(3)) depletion at high latitudes in the springtime, several related atmospheric species, including O(3), chlorine monoxide(ClO), and bromine monoxide (BrO) were measured in the lower stratosphere with instruments mounted on the NASA ER-2 aircraft on 13 February 1988. The flight path from Moffett Field, California (37 degrees N, 121 degrees W), to Great Slave Lake, Canada (61 degrees N, 115 degrees W), extended to the center of the polar jet associated with but outside of the Arctic vortex, in which the abundance of O(3) was twice its mid-latitude value, whereas BrO levels were 5 parts per trillion by volume (pptv) between 18 and 21 kilometers, and 2.4 pptv below that altitude. The ClO mixing ratio was as much as 65 pptv at 60 degrees N latitude at an altitude of 20 kilometers, and was enhanced over mid-latitude values by a factor of 3 to 5 at altitudes above 18 kilometers and by as much as a factor of 40 at altitudes below 17 kilometers. Levels of ClO and O(3) were highly correlated on all measured distance scales, and both showed an abrupt change in character at 54 degrees N latitude. The enhancement of ClO abundance north of 54 degrees N was most likely caused by low nitrogen dioxide levels in the flight path.

Rising bromine levels threaten ozone layer

Concerns that man-made brominecontaining halocarbons, in addition to chlorofluorocarbons (CFCs), are helping destroy Earth's ozone layer intensified last week when a team of researchers reported that atmospheric levels of two such bromine compounds are on the rise. The researchers conducted several balloon experiments from 1980 to 1987 to measure the atmospheric abundance of Halon-1211 (CBrClF 2 ) and Halon-1301 (CBrF 3 ), which are used to extinguish fires. They found that atmospheric levels of these gases are increasing 12% and 5% per year, respectively. The concentration of CBrClF 2 is currently about 2 parts per trillion by volume (pptv) and that of CBrF3 is about 1.3 pptv, they found. These readings were made at altitudes of 10 to 15 km over southern France (44° N) and south central India (17.5° N). Scientists are concerned because CBrClF 2 and CBrF 3 are important sources of bromine oxides, which can deplete ozone more efficiently than chlorine oxides. Moreover, bromine monoxide (BrO) and chlorine m...

Formation of bromine chloride(3.PI.0+) in the reaction of bromine monoxide with chlorine monoxide

Observations of bromine atom yields from the reaction of BrO with ClO indicate the presence of a third product channel in addition to channels which form Br + OClO and Br + ClOO. The authors argue that this process is a four-center elimination of vibrationally excited BrCl(/sup 3/II/sub 0/sup +//) and O/sub 2/(/sup 3/..sigma../sub g//sup -/) from an internally excited singlet BrOOCl intermediate. The excited BrCl subsequently is quenched, predissociates, or fluoresces; the latter process has been observed previously in the Br/sub 2/ + OClO chain reaction system. This mechanism may commonly occur in the halogen monoxide disproportionation reactions. The implications of this new channel for kinetic measurements and models of stratospheric ozone depletion are significant.

The collision‐induced linewidths of chlorine and bromine monoxide perturbed by nitrogen

By using the semiclassical, perturbative theory formulated by Mehrotra and Boggs, the J and temperature dependence of line width parameter is computed for ClO‐N2 and BrO‐N2 systems. The temperature dependence is found to be J dependent. As per these calculations the value of the line width parameter for the ClO‐N2 system is at least 35% higher at the temperature T = 300°K, and also the temperature dependence is different from that of the value of Waters et al. However, this disagreement is within the uncertainty range stated by them.

Free Radical Bromination of Saturated Hydrocarbons using Bromine and Mercuric Oxide

The reaction of alkanes with a mixture of bromine and mercuric oxide gives alkyl bromides in preparatively useful yields. The reagent is significantly more reactive than elemental bromine, and it is believed that bromine monoxide, formed insitu by the interaction of bromine and mercury oxide, is the reactive intermediate. Bromination by bromine monoxide is a free radical chain process in which hydrogen abstraction is carried out predominantly by bromoxy (BrO•) radicals, and to a lesser extent by bromine atoms.