http://joenschem.com/yahoo_site_admin/assets/docs/atkinson2000r.93190106.pdf

Atmospheric chemistry of VOCs and NOx

In this Account we have compiled a list of reliable bond energies that are based on a set of critically evaluated experiments. A brief description of the three most important experimental techniques for measuring bond energies is provided. We demonstrate how these experimental data can be applied to yield the heats of formation of organic radicals and the bond enthalpies of more than 100 representative organic molecules.

Bond Dissociation Energies of Organic Molecules

Atmospheric degradation of volatile organic compounds

We present and discuss a new dataset of gridded emissions covering the historical period (1850–2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude. The primary purpose of this inventory is to provide consistent gridded emissions of reactive gases and aerosols for use in chemistry model simulations needed by climate models for the Climate Model Intercomparison Program #5 (CMIP5) in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). Our best estimate for the year 2000 inventory represents a combination of existing regional and global inventories to capture the best information available at this point; 40 regions and 12 sectors are used to combine the various sources. The historical reconstruction of each emitted compound, for each region and sector, is then forced to agree with our 2000 estimate, ensuring continuity between past and 2000 emissions. Simulations from two chemistry-climate models is used to test the ability of the emission dataset described here to capture long-term changes in atmospheric ozone, carbon monoxide and aerosol distributions. The simulated long-term change in the Northern mid-latitudes surface and mid-troposphere ozone is not quite as rapid as observed. However, stations outside this latitude band show much better agreement in both present-day and long-term trend. The model simulations indicate that the concentration of carbon monoxide is underestimated at the Mace Head station; however, the long-term trend over the limited observational period seems to be reasonably well captured. The simulated sulfate and black carbon deposition over Greenland is in very good agreement with the ice-core observations spanning the simulation period. Finally, aerosol optical depth and additional aerosol diagnostics are shown to be in good agreement with previously published estimates and observations.

/pdf/historical-1850-2000-gridded-anthropogenic-and-biomass-3byr14xpsp.pdf

Historical (1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application

 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

This is the eighteenth in a series of evaluated sets of rate constants, photochemical cross sections, heterogeneous parameters, and thermochemical parameters compiled by the NASA Panel for Data Evaluation. The data are used primarily to model stratospheric and upper tropospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena. The evaluation is available in electronic form from the following Internet URL: http://jpldataeval.jpl.nasa.gov/

/pdf/chemical-kinetics-and-photochemical-data-for-use-in-1i2ookqvpk.pdf

Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies: Evaluation Number 18

The conventional flash photolysis-resonance fluorescence technique was employed to study reactions of OH with CH/sub 3/SCH/sub 3/ (1), CD/sub 3/SCD/sub 3/ (2), CH/sub 3/SC/sub 2/H/sub 5/ (3), and C/sub 2/H/sub 5/SC/sub 2/H/sub 5/ (4) in argon buffer gas. Reactivity trends, temperature dependencies, and isotope effects suggest that hydrogen abstraction is the dominant observed reaction pathway under these conditions. A pulsed-laser photolysis-pulsed-laser-induced fluorescence technique was employed to study reactions 1 and 2 in N/sub 2/, air, and O/sub 2/ buffer gases. Complex kinetics were observed in the presence of O/sub 2/. A four-step mechanism involving hydrogen abstraction, reversible addition to the sulfur atom, and scavenging of the (thermalized) adduct by O/sub 2/ is required to explain all experimental observations. In 1 atm of air, the effective bimolecular rate constant for reaction 1 decreases monotonically from 1.58 x 10/sup -11/ to 5.2 x 10/sup -12/ cm/sup 3/ molecule/sup -1/s/sup -1/ over the lower tropospheric temperature range 250-310 K. Over the same temperature range the branching ratio for hydrogen abstraction increases monotonically from 0.24 to 0.87. At 261 K, the rate constant for unimolecular decomposition of the CD/sub 3/S(OH)CD/sub 3/ adduct is (3.5 +/- 2.0) x 10/sup 6/ s/sup -1/ and the rate more » constant for the adduct reaction with O/sub 2/ is (4.2 +/- 2.2) x 10/sup -12/ cm/sup 3/ molecule/sup -1/s/sup -1/. « less

Kinetics and mechanism of OH reactions with organic sulfides

NASA Data Evaluation: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies

Absolute rate constants for the reactions of the hydroxyl radical with benzene and toluene were measured within the temperature and pressure ranges 213 less than or equal to T less than or equal to 1150 K and 20 less than or equal to P less than or equal to 200 torr by using He, Ar, and SF/sub 6/ as diluent gases. To help elucidate the variations in reaction mechanism with temperature, we also studied OH reactions with deuterated benzene (C/sub 6/D/sub 6/) and with selectively deuterated toluenes (C/sub 6/H/sub 5/CD/sub 3/, C/sub 6/D/sub 5/CD/sub 3/, and C/sub 6/D/sub 5/CH/sub 3/). Three major reaction channels were characterized kinetically. At T less than or equal to 298 K, electrophilic addition of the OH radical to the aromatic ring is the dominant reactive pathway in all systems studied. At temperatures above 500 K, rapid decomposition of the thermalized adduct back to reactants diminishes the importance of the addition channel and leads to bimolecular reaction rate-constant values significantly lower than those measured near room temperature. At elevated temperatures, the ring hydrogen abstraction (for benzene) and side-chain hydrogen abstraction (for toluene) pathways are shown to be predominant. The measured bimolecular rate constants increase monotonically withmore » increases in temperature above 500 K, and kinetic separation of the two hydrogen abstraction modes for toluene is achieved.« less

Kinetics of the reactions of hydroxyl radical with benzene and toluene

A laser flash photolysis/long path absorption technique has been employed to study at 298 K the kinetics of aqueous phase reactions of the SO4− radical with a number of species commonly found in cloud water. Much lower radical concentrations were employed than in all previous direct studies of SO4− reaction kinetics. In the zero ionic strength limit, rate coefficients for SO4− reactions with the anions HSO3−, Cl−, NO2−, HCOO−, and CH3COO− are found to be 7.5 × 108, 2.6 × 108, 9.8 × 108, 1.1 × 108, and 3.7 × 106 M−1 s−1, respectively. Rate coefficients for SO4− reactions with the neutral species H2O2, CH3OH, HCOOH, and CH3COOH are found to be 1.2 × 107, 8.8 × 106, 4.6 × 105, and 1.4 × 104 M−1 s−1, respectively. For many of the reactions studied, agreement with previously reported rate data is poor. Of particular importance for cloud chemistry is the fact that the SO4− + HSO3− reaction proceeds more slowly than previously believed, while the SO4− + Cl− reaction is somewhat faster than previously thought. Incorporation of these results into cloud chemistry models should reduce the calculated efficiency of free radical chain reactions as an oxidation mechanism for S IV.

Paul H. Wine

Papers

Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies: Evaluation Number 18

Kinetics and mechanism of OH reactions with organic sulfides

NASA Data Evaluation: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies

Kinetics of the reactions of hydroxyl radical with benzene and toluene

Kinetics of aqueous phase reactions of the SO4 − radical with potential importance in cloud chemistry