 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

(b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

The Quantum Theory of Light

On-line monitoring of volatile organic compounds at pptv levels by means of proton-transfer-reaction mass spectrometry (PTR-MS) medical applications, food control and environmental research

Large polycyclic aromatic hydrocarbon (PAH) molecules carry the infrared (IR) emission features that dominate the spectra of most galactic and extragalactic sources. This review surveys the observed mid-IR characteristics of these emission features and summarizes laboratory and theoretical studies of the spectral characteristics of PAHs and the derived intrinsic properties of emitting interstellar PAHs. Dedicated experimental studies have provided critical input for detailed astronomical models that probe the origin and evolution of interstellar PAHs and their role in the universe. The physics and chemistry of PAHs are discussed, emphasizing the contribution of these species to the photoelectric heating and the ionization balance of the interstellar gas and to the formation of small hydrocarbon radicals and carbon chains. Together, these studies demonstrate that PAHs are abundant, ubiquitous, and a dominant force in the interstellar medium of galaxies.

Interstellar Polycyclic Aromatic Hydrocarbon Molecules

. Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing. All EFs are converted to one standard form (g compound emitted per kg dry biomass burned) using the carbon mass balance method and they are categorized into 14 fuel or vegetation types. Biomass burning terminology is defined to promote consistency. We compile a large number of measurements of biomass consumption per unit area for important fire types and summarize several recent estimates of global biomass consumption by the major types of biomass burning. Post emission processes are discussed to provide a context for the emission factor concept within overall atmospheric chemistry and also highlight the potential for rapid changes relative to the scale of some models or remote sensing products. Recent work shows that individual biomass fires emit significantly more gas-phase NMOC than previously thought and that including additional NMOC can improve photochemical model performance. A detailed global estimate suggests that BB emits at least 400 Tg yr−1 of gas-phase NMOC, which is almost 3 times larger than most previous estimates. Selected recent results (e.g. measurements of HONO and the BB tracers HCN and CH3CN) are highlighted and key areas requiring future research are briefly discussed.

/pdf/emission-factors-for-open-and-domestic-biomass-burning-for-20tklb2vkv.pdf

Emission factors for open and domestic biomass burning for use in atmospheric models

Gobet et al. Reply

We have recently constructed the tandem mass spectrometer set-up BESTOF (consisting of a B-sector field combined with an E-sector field, a Surface and a Time Of Flight mass spectrometer) which allows the investigation of ion/surface reactions with high primary mass and energy resolution. Using BESTOF we have extended previous investigations from molecular projectile ions to cluster ions. In particular, we have studied here surface induced dissociation (SID) and surface induced reactions (SIR) of acetone dimer ions upon impact on a hydrocarbon covered stainless steel surface as a function of incident collision energy up to about 80 eV.

Low energy acetone dimer ion/surface collisions studied with high energy resolution

Investigation of several halogenated organic compounds reacting with O2+• using selective reagent ion-time-of-flight-mass spectrometry

Erratum: Absolute partial and total electron impact ionization cross sections for CF4 from threshold up to 180 eV [J. Chem. Phys. 83, 5712 (1985)]

A supersonic jet of cold neutral van der Waals clusters consisting of Ar and Ne atoms was sent through a Nier-type ion source and allowed to interact with thermal Xe ions produced therein via dissociative ion capture (DIC). A comparison of the resulting ions of the type Ar n Xe+ and Ne n Xe+ with pure Ar and Ne cluster ion distributions produced by electron impact (EI) of the same neutral vdW cluster precursor distribution shows characteristic differences in the overall shape of the distribution and in the ion stabilities (i.e. in the occurence of magic numbers in the mass spectra). To shed more light onto these differences we performed classical molecular dynamic calculations (MD) on the dynamics and Kinetics of these two ionization processes (DIC and EI) and found good agreement between the experimental results and the results deduced from these simulations.

Tilmann D. Märk

Papers

Gobet et al. Reply

Low energy acetone dimer ion/surface collisions studied with high energy resolution

Investigation of several halogenated organic compounds reacting with O2+• using selective reagent ion-time-of-flight-mass spectrometry

Erratum: Absolute partial and total electron impact ionization cross sections for CF4 from threshold up to 180 eV [J. Chem. Phys. 83, 5712 (1985)]

Xe+-ion capture by neutral Ar and Ne clusters