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14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Dibromine Monoxide, Br2O: The Rotational Spectrum and Molecular Properties

The rotational spectra of (79)Br2O, (79)BrO(81)Br, and Br2O in their ground vibrational states as well as (79)BrO(81)Br in its v (sub 2) = 1 state have been studied in selected regions between 90 and 523 GHz. Transitions involving a large range of quantum numbers, 6 less than or equal to J less than or equal to 123 and 0 less than or equal to K (sub a) less than or equal to 12, have been observed permitting precise rotational and a large set of centrifugal distortion constants to be determined. All isotopic species as well as the excited state data were fit simultaneously. Ground-state effective and average structural parameters as well as an estimate of the equilibrium structure have been derived. The quartic distortion constants were used for a calculation of the harmonic force field. The complete quadrupole tensor has been determined. Its diagonalization reveals a largely covalent BrO bond with little pi-bonding. The derived properties of Br2O are compared with those of related compounds such as Cl2O, HOBR, and HOCl.

Mueller, Holger S. P.↗
DOE OSTI2020

Materials Data on Br2O by Materials Project

OBr2 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pna2_1 space group. The structure is zero-dimensional and consists of four bromoether molecules. O is bonded in a bent 120 degrees geometry to two Br atoms. There is one shorter (1.87 Å) and one longer (1.98 Å) O–Br bond length. There are two inequivalent Br sites. In the first Br site, Br is bonded in a single-bond geometry to one O atom. In the second Br site, Br is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs2U(Br2O)2 by Materials Project

Cs2U(OBr2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Cs1+ is bonded in a 10-coordinate geometry to two equivalent O2- and eight Br1- atoms. There are one shorter (3.30 Å) and one longer (3.47 Å) Cs–O bond lengths. There are a spread of Cs–Br bond distances ranging from 3.70–4.13 Å. U6+ is bonded in a distorted linear geometry to two equivalent O2- and four Br1- atoms. Both U–O bond lengths are 1.81 Å. There are two shorter (2.83 Å) and two longer (2.84 Å) U–Br bond lengths. O2- is bonded in a distorted single-bond geometry to two equivalent Cs1+ and one U6+ atom. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 1-coordinate geometry to four equivalent Cs1+ and one U6+ atom. In the second Br1- site, Br1- is bonded in a 1-coordinate geometry to four equivalent Cs1+ and one U6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbH7(Br2O)3 by Materials Project

SbBr6H2OH5O2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four molecular hydrogen;dihydrate molecules, four water molecules, and four SbBr6 clusters. In each SbBr6 cluster, Sb5+ is bonded in an octahedral geometry to six Br1- atoms. There are a spread of Sb–Br bond distances ranging from 2.60–2.63 Å. There are six inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom. In the second Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom. In the third Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom. In the fourth Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom. In the fifth Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom. In the sixth Br1- site, Br1- is bonded in a single-bond geometry to one Sb5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaH4Au(Br2O)2 by Materials Project

NaAuH4(OBr2)2 crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two NaAuH4(OBr2)2 sheets oriented in the (0, 0, 1) direction. Na1+ is bonded in a 4-coordinate geometry to four equivalent O2- and three Br1- atoms. There are two shorter (2.43 Å) and two longer (2.55 Å) Na–O bond lengths. There are a spread of Na–Br bond distances ranging from 3.15–3.29 Å. Au3+ is bonded in a rectangular see-saw-like geometry to four Br1- atoms. There are a spread of Au–Br bond distances ranging from 2.47–2.49 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. There are four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted bent 120 degrees geometry to one Na1+ and one Au3+ atom. In the second Br1- site, Br1- is bonded in a distorted water-like geometry to one Na1+ and one Au3+ atom. In the third Br1- site, Br1- is bonded in a water-like geometry to one Na1+ and one Au3+ atom. In the fourth Br1- site, Br1- is bonded in a single-bond geometry to one Au3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAu(Br2O)2 by Materials Project

KAu(OBr2)2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of two KAu(OBr2)2 ribbons oriented in the (1, 0, 1) direction. K1+ is bonded in a linear geometry to two equivalent O2- atoms. Both K–O bond lengths are 2.61 Å. Au1+ is bonded in a square co-planar geometry to four Br+0.50+ atoms. There are two shorter (2.47 Å) and two longer (2.60 Å) Au–Br bond lengths. O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and one Br+0.50+ atom. The O–Br bond length is 1.74 Å. There are two inequivalent Br+0.50+ sites. In the first Br+0.50+ site, Br+0.50+ is bonded in a single-bond geometry to one Au1+ atom. In the second Br+0.50+ site, Br+0.50+ is bonded in a bent 120 degrees geometry to one Au1+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KAu(Br2O)2 by Materials Project

KAu(OBr2)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two KAu(OBr2)2 sheets oriented in the (0, 1, 0) direction. K1+ is bonded in a distorted square co-planar geometry to four equivalent O2- atoms. There are two shorter (2.72 Å) and two longer (2.88 Å) K–O bond lengths. Au1+ is bonded in a square co-planar geometry to four Br+0.50+ atoms. There are two shorter (2.46 Å) and two longer (2.59 Å) Au–Br bond lengths. O2- is bonded in a trigonal non-coplanar geometry to two equivalent K1+ and one Br+0.50+ atom. The O–Br bond length is 1.74 Å. There are two inequivalent Br+0.50+ sites. In the first Br+0.50+ site, Br+0.50+ is bonded in a single-bond geometry to one Au1+ atom. In the second Br+0.50+ site, Br+0.50+ is bonded in a distorted water-like geometry to one Au1+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaB24S6(Br2O)12 by Materials Project

Na(SO2)6(BBr)24 crystallizes in the trigonal P-31c space group. The structure is zero-dimensional and consists of forty-eight bromoborane molecules and two Na(SO2)6 clusters. In each Na(SO2)6 cluster, Na1+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Na–O bond lengths are 2.44 Å. S+1.17- is bonded in a bent 120 degrees geometry to two O2- atoms. Both S–O bond lengths are 1.45 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S+1.17- atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Na1+ and one S+1.17- atom.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Ab Initio Characterization of Triatomic Bromine Molecules of Potential Interest in Stratospheric Chemistry

The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determined using the CCSD(T) electron correlation method in conjunction with a basis set of triple zeta double polarized (TZ2P) quality. Specifically, the molecules included in the present study are HOBr, HBrO, FOBr, FBrO, BrNO, BrON, Br2O, BrBrO, BrCN, BrNC, ClOBr, ClBrO, and BrClO. Very accurate isomeric energy differences have also been determined at the CCSD(T) level with atomic natural orbital basis sets that include through g-type functions. In most cases, the isomer with a normal neutral Lewis dot structure is the lowest energy form, with the single exception that FBRO is predicted to be 11.1 kcal/mol (0 K) lower in energy than FOBr. In all cases, however, the hypervalent isomer is more stable relative to the isomer with a normal Lewis dot structure as compared to the chlorine analogs. Consistent with this observation, the energy of the last three molecules given above increases in the order ClOBr less than ClBrO less than BrClO. The CCSD(T)/TZ2P geometries and vibrational frequencies are in good agreement with the available experimental data. Heats of formation are determined for all species using a combination of theoretical isomeric, homodesmic, and isodesmic reaction energies. The accuracy of these quantities is ultimately dependent on the reliability of the experimental heat of formation of HOBr.

Lee. Timothy J.↗
NASA NTRS1995

Ab Initio Characterization of Triatomic Bromine Molecules of Potential Interest in Stratospheric Chemistry

The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determined using the CCSD(T) electron correlation method in conjunction with a basis set of triple zeta double polarized (TZ2P) quality. Specifically, the molecules included in the present study are HOBr, HBrO, FOBr, FBrO, BrNO, BrON, Br2O, BrBrO, BrCN, BrNC, ClOBr, ClBrO, and BrClO. Very accurate isomeric energy differences have also been determined at the CCSD(T) level with atomic natural orbital basis sets that include through g-type functions. In most cases, the isomer with a normal neutral Lewis dot structure is the lowest energy form, with the single exception that FBrO is predicted to be 11.1 kcal/mol (0 K) lower in energy than FOBr. In all cases, however, the hypervalent isomer is more stable relative to the isomer with a normal Lewis dot structure as compared to the chlorine analogs. Consistent with this observation, the energy of the last three molecules given above increases in the order ClOBr less than ClBrO less than BrClO. The CCSD(T)/TZ2P geometries and vibrational frequencies are in good agreement with the available experimental data. Heats of formation are determined for all species using a combination of theoretical isomeric, homodesmic, and isodesmic reaction energies. The accuracy of these quantities is ultimately dependent on the reliability of the experimental heat of formation of HOBr.

Lee, Timothy J.↗
NASA NTRS2001

Heterogeneous Uptake and Conversion of HOBr on H2SO4 at Upper Tropospheric and Stratospheric Temperatures (255 - 210 K)

Halogen species are known to catalytically destroy ozone in several different regions of the atmosphere. In addition to directly destroying ozone, bromine compounds can indirectly enhance ozone loss through coupling to other radical families. Hypobromous acid (HOBr), a key species in the linkage of BrOx to ClOx and HOx, is produced by the hydrolysis of BrONO2 on sulfate aerosols, and thus the heterogeneous behavior of HOBr must be understood. We have measured the solubility of HOBr in 45 to 70 percent by weight sulfuric acid solutions. Over the temperature range 208 to 255 K, HOBr is very soluble in sulfuric acid, H(*) = 10(exp 4) to 10(exp 8) M/atm. The solubility is temperature dependent, and our results agree well with those of Waschewsky and Abbott for 60 percent by weight H2SO4. HOBr is nearly as soluble as HBr, indicating that equilibrium concentrations of HOBr could approach those of HBr in sulfuric acid aerosols. Despite the high solubility of HOBr, stratospheric aerosol volumes are not large enough to sequester a significant fraction of inorganic bromine from the gas phase. Uptake of HOBr was nearly always accompanied by reaction, producing Br2O and possibly Br2. The effect of this bromine conversion pathway on the HOx and ClOx families, particularly at temperatures as warm as 255 K, will be considered.

Iraci, Laura T.↗
NASA NTRS2004

Solubility of HOBr in Acidic Solution and Implications for Liberation of Halogens Via Aerosol Processing

Halogen species are known to catalytically destroy ozone in several regions of the atmosphere. In addition to direct catalytic losses, bromine compounds can indirectly enhance ozone loss through coupling to other radical families. Hypobromous acid (HOBr) is a key species in the linkage of BrOx to ClOx and HOx. The aqueous- phase coupling reaction HOBr + HCI (right arrow) BrCl + H2O may provide a pathway for chlorine activation on sulfate aerosols at temperatures warmer than those required for polar stratospheric cloud formation. We have measured t h e solubility of HOBr in 45 - 70 wt% sulfuric acid solutions. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, H* = 10(exp 4) - 10(exp 7) mol dm(exp -3) atm(exp -1). The expected inverse dependence of H* on temperature was observed, but only a weak dependence on acidity was found. The solubility of HOBr is comparable to that of HBr, indicating that equilibrium concentrations of HOBr could equal or exceed those of HBr in upper tropospheric and lower stratospheric aerosols. Despite the high solubility of HOBr, aerosol volumes are not large enough to sequester a significant fraction of inorganic bromine from the gas phase. Our measurements of HOBr uptake in aqueous sulfuric acid in the presence of other brominated gases show the evolution of gaseous products including Br2O and Br2.

Iraci, Laura T.↗
NASA NTRS2005

Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

Iraci, Laura T.↗