Synthesis and identification by infrared spectroscopy of gaseous nitryl bromide, BrNO2

Finlayson-Pitts, Barbara J.; Livingston, Frank E.; Berko, H.

doi:10.1021/j100348a005

Cited by 39 publications

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“…[11][12][13][14] The u 1 diagnostic 19,31 for BrNO 2 is similar to that observed previously 18 for ClNO 2 and indicates that the CCSD(T) level of theory will perform very well in this situation. No experimental information for the structure of BrNO 2 is available.…”

Section: A Equilibrium Structures and Vibrational Frequenciessupporting

confidence: 79%

Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Lee

1996

J. Phys. Chem.

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The titled compounds are investigated using large one-particle basis sets in conjunction with the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Accurate geometries, dipole moments, harmonic vibrational frequencies, and IR intensities are determined. Agreement with the available experimental data (which is limited to fundamental vibrational frequencies) is very good except for the Br-N stretching mode in BrNO 2 . Convincing theoretical and experimental arguments are presented which indicate that the experimental assignment for the Br-N fundamental is in error. Accurate isomerization energies are determined at the CCSD(T) level using spdfg one-particle basis sets. Comparison of ab initio results for the titled compounds with previously published ab initio results from the fluorine and chlorine analogs elucidates several trends involving equilibrium geometries, bonding characteristics, and relative energies. Heats of formation of all three titled compounds are evaluated and used to show that BrNO 2 and cis-BrONO are sufficiently thermally stable to exist in the Earth's stratosphere. Possible stratospheric formation and destruction mechanisms are discussed.

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Section: A Equilibrium Structures and Vibrational Frequenciessupporting

confidence: 79%

Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Lee

1996

J. Phys. Chem.

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“…Guided by the only previous study of the reaction of a bromide with N 2 O 5 , where it was determined that BrNO 2 is formed as a principal product, 24 we anticipated the following process for reaction 6:…”

Section: Resultsmentioning

confidence: 99%

Heterogeneous Kinetics of N₂O₅Uptake on Salt, with a Systematic Study of the Role of Surface Presentation (for N₂O₅and HNO₃)

1996

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The kinetics for the uptake of N 2 O 5 with NaCl [N 2 O 5 (g) + NaCl(s) f ClNO 2 (g) + NaNO 3 (s) (reaction 1)] and KBr[N 2 O 5 (g) + KBr(s) f products (reaction 6)] have been studied in a Teflon-coated Knudsen reactor. The product of reaction 1 is found to be ClNO 2 , in agreement with previous studies. The only brominecontaining gaseous product observed for reaction 6 is Br 2 ; we propose a redox reaction in which Br -is oxidized to molecular bromine with the concurrent formation of nitrite. The hypothesis is supported by the observation of nitrous acid in the product spectrum of reaction 6. The observed uptake coefficients are found to depend strongly on the total external surface area of the salt substrates, prepared by a number of methods. With samples of well-defined total external surface, we are able to determine the following values for the uptake coefficient: γ 1 ) (5.0 ( 2.0) × 10 -4 ; γ 6 ) (4.0 ( 2.0) × 10 -3 . The values are smaller than previously reported. The unexpected dependence of the uptake kinetics on the surface presentation led us to conduct further experiments on the HNO 3 reaction with salt: HNO 3 (g) + NaCl(s) f HCl(g) + NaNO 3 (s) (reaction 2). From our new experiments conducted on various substrates, we find γ 2 ) (2.0 ( 1.0) × 10 -2 , in good agreement with our previous measurements on salt powder. The validity of calculating correction factors for the uptake coefficients, as recently proposed by Keyser and co-workers, is discussed in detail, and specific experimental tests of the theory are described. The role of internal surfaces in the overall observed uptake kinetics for the reactions of N 2 O 5 is found to be remarkably well described by the treatment given by Keyser and co-workers. Additional experiments on the uptake kinetics of nitric acid, however, cast doubt that this treatment can be generally extended to all species of atmospheric interest. The atmospheric implications of these findings are discussed briefly.

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“…These molecules are important sources of chlorine and bromine atoms, which is turn have been implicated in catalytic ozone depletion. 5 Important surface processes such as these frequently take place preferentially at defect sites, such as steps, adatoms, or vacancies. For example, the contact charging of NaCl is believed to be mediated by adsorption of H20 in surface cation vacancies: and dissociative adsorption of H20 occurs at C1-vacancies on a NaCl film.6 However, an elucidation of defectcontrolled surface processes is difficult to obtain: sophisticated surface preparation and analysis techniques are needed to investigate processes at various defect sites such as adatoms' and steps.…”

Section: Introductionmentioning

confidence: 99%

Molecular Adsorption-Desorption Reactions of Ammonia on Alkali Halide Clusters and Nanocrystals

Homer¹,

Livingston

Whetten³

1995

J. Phys. Chem.

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The initial adsorption of ammonia molecules (NH3) on larger alkali halide clusters and small nanocrystals (mainly NaF) has been investigated by flow-reactor methods as a function of cluster size and temperature.An analysis of the strong size-dependent reactivity of positively-charged NaF clusters, along with their computed structures, indicates that a particular type of defect in the nanocrystal structure facilitates adsorption. This defect is formed by removing an ion-pair from adjoining face and internal sites of a perfect crystallite, creating a basket-like opening. KF nanocrystals show very similar reactivity patterns, reflecting their corresponding structures, but LiF clusters follow a different pattern. It was established that NH3 adsorption on preformed NaF nanocrystals takes place under equilibrium conditions. The equilibrium constant for initial adsorptiondesorption increases with decreasing temperature (250-340 K) and allows one to derive heats of N H 3 adsorption near 0.2 eV for the more reactive (defective) nanocrystals. The much lower reactivity of negatively-charged clusters is ascribed to an additional kinetic-dynamic barrier to adsorption.

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Synthesis and identification by infrared spectroscopy of gaseous nitryl bromide, BrNO2

Cited by 39 publications

References 0 publications

Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Heterogeneous Kinetics of N₂O₅Uptake on Salt, with a Systematic Study of the Role of Surface Presentation (for N₂O₅and HNO₃)

Molecular Adsorption-Desorption Reactions of Ammonia on Alkali Halide Clusters and Nanocrystals

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Synthesis and identification by infrared spectroscopy of gaseous nitryl bromide, BrNO2

Cited by 39 publications

References 0 publications

Characterization of BrNO2, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Characterization of BrNO2, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Heterogeneous Kinetics of N2O5Uptake on Salt, with a Systematic Study of the Role of Surface Presentation (for N2O5and HNO3)

Molecular Adsorption-Desorption Reactions of Ammonia on Alkali Halide Clusters and Nanocrystals

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Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Characterization of BrNO₂, cis-BrONO, and trans-BrONO. Implications for Atmospheric Chemistry

Heterogeneous Kinetics of N₂O₅Uptake on Salt, with a Systematic Study of the Role of Surface Presentation (for N₂O₅and HNO₃)